Underwent or Undergone? The Correct Past Tense of “Undergo” explains why these two forms of the irregular verb undergo are correct but serve different grammatical purposes.
In English grammar, undergo is the base or infinitive form, underwent is the simple past form, and undergone is the past participle form. The key difference is tense and sentence construction.
underwent normally describes a completed action, isolated incident, or past event, while undergone generally appears with an auxiliary verb such as has, have, or had to form perfect tenses. When talking about something that happened and finished fully in the past, the simple past form underwent is usually the correct choice.
Quick Answer: Underwent or Undergone?
Underwent is the correct simple past tense of undergo.
Undergone is the correct past participle and usually appears with an auxiliary verb such as has, have, or had.
| Form | Grammatical role | Example |
| undergo | Base form | Patients may undergo further testing. |
| underwent | Simple past | She underwent surgery last year. |
| undergone | Past participle | She has undergone surgery. |
| undergoing | Present participle | She is undergoing treatment. |
| undergoes | Third-person singular present | The system undergoes regular testing. |
The easiest rule is this:
Use “underwent” for the simple past. Use “undergone” after has, have, or had.
For example:
- Correct: He underwent an examination yesterday.
- Correct: He has undergone an examination.
- Correct: He had undergone an examination before the procedure.
- Incorrect: He has undergone an examination.
- Incorrect: He underwent an examination yesterday.
Cambridge specifically identifies underwent as the past tense and undergone as the past participle.
What Does “Undergo” Mean?
The verb undergo means to experience, pass through, or be subjected to something, especially a process, change, treatment, test, or difficult experience.
It often describes something that happens to a person, organization, object, or system.
For example:
- The patient underwent surgery.
- The company underwent major changes.
- The building underwent extensive repairs.
- The product underwent several safety tests.
- The country is undergoing significant economic changes.
The word often carries a slightly formal tone. That’s why you frequently see it in medical writing, business reports, academic research, technical documents, and formal communication.
Oxford gives examples such as undergoing tests, trials, and repairs. It also lists undergo as a verb meaning to experience something, particularly a change or something unpleasant.
Is “Undergo” a Regular or Irregular Verb?
Undergo is an irregular verb.
A regular verb usually forms its past tense with -ed:
- walk → walked
- examine → examined
- change → changed
But undergo doesn’t become undergoed. Instead, its forms change irregularly:
undergo → underwent → undergone
That’s why memorizing its three principal forms is useful.
What Is the Past Tense of “Undergo”?
The simple past tense of undergo is underwent.
Use underwent when you’re describing an action or experience that happened in the past.
Examples of “Underwent” in the Simple Past
- She underwent surgery last month.
- The building underwent extensive renovations.
- The company underwent a major restructuring in 2024.
- The machine underwent several safety tests.
- He underwent intensive training before joining the team.
Notice something important in these sentences. Underwent doesn’t need has, have, or had.
It functions as the main past-tense verb.
“Underwent” With Specific Past Time
Underwent works especially naturally when you mention a finished period or specific point in the past.
Common time expressions include:
- yesterday
- last week
- last year
- in 2023
- two months ago
- during the summer
- before the meeting
For example:
The hospital underwent major renovations in 2023.
The renovation happened during a clearly identified past period. Therefore, underwent fits naturally.
What Is “Undergone” and When Do You Use It?
Undergone is the past participle of undergo. It isn’t the simple past form.
The past participle generally works with an auxiliary verb to create perfect tenses.
The most common combinations are:
- has undergone
- have undergone
- had undergone
For example:
The company has undergone significant changes.
Here, has is the auxiliary verb and undergone is the past participle.
Compare that with:
The company underwent significant changes last year.
Both sentences can describe a completed change. However, their grammatical structures and time perspectives differ.
“Has Undergone”
Use has undergone a singular third-person subject.
Examples:
- The company has undergone major changes.
- She has undergone several tests.
- The building has undergone extensive repairs.
- The system has undergone several upgrades.
“Have Undergone”
Use have undergone with I, you, we, they, and plural nouns.
Examples:
- They have undergone extensive training.
- We have undergone several changes.
- The products have undergone safety testing.
- Many employees have undergone additional training.
“Had Undergone”
Use has undergone when you need the past perfect.
For example:
By the time the inspection began, the building had undergone several repairs.
The repairs happened first. The inspection happened later.
That sequence is exactly what the past perfect can clarify.
Undergo Verb Forms at a Glance
| Verb form | Correct word | Example |
| Base form | undergo | They may undergo testing. |
| Simple past | underwent | They underwent testing yesterday. |
| Past participle | undergone | They have undergone testing. |
| Present participle | undergoing | They are undergoing testing. |
| Third-person singular | undergoes | The system undergoes testing regularly. |
Cambridge and Oxford both confirm this verb pattern.
The three forms worth memorizing first are:
undergo — underwent — undergone
Once you remember that sequence, many common errors disappear.
Underwent vs. Undergone in Sentences
The easiest way to understand the difference is to place the two forms side by side.
Using “Underwent” for Completed Past Events
Use underwent when the sentence uses the simple past.
Maria underwent surgery in June.
The sentence describes a completed event at a particular time.
Another example:
The factory underwent major renovations last year.
Again, underwent works because the sentence describes a completed past event.
Using “Undergone” With the Present Perfect
Now consider this sentence:
Maria has undergone surgery.
The construction is different.
The word has creates the present perfect, while undergone supplies the past participle.
You could also say:
The factory has undergone major renovations.
The present perfect can emphasize a past event that remains relevant to the present or occurred within a period connected to the present.
Using “Undergone” With the Past Perfect
Consider:
The factory had undergone renovations before the new owner arrived.
Two past events appear:
- The factory underwent renovations.
- The new owner arrived.
The renovations happened first, so had undergone places that event earlier in the past.
“Underwent” vs. “Has Undergone”: What’s the Difference?
This is one of the most useful distinctions to understand.
Compare these sentences:
The patient underwent treatment in May.
The patient has undergone treatment.
The first sentence uses the simple past and identifies a completed event at a specific past time.
The second uses the present perfect. It connects the past experience to the present situation.
A useful comparison looks like this:
| Sentence | Tense | Main idea |
| She underwent treatment in May. | Simple past | Finished event at a stated past time |
| She has undergone treatment. | Present perfect | Past event connected to the present |
| She had undergone treatment before June. | Past perfect | Event completed before another past event |
A Simple Time Test
Ask yourself whether you’re naming a finished pastime.
If you are, underwent will often be the natural choice:
He underwent surgery in 2022.
If you’re using has, have, or had, you need undergone:
He has undergone surgery.
He had undergone surgery before the accident.
This isn’t the only consideration in every sentence, but it’s an excellent practical rule.
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“Underwent” vs. “Had Undergone”
These two forms are both past constructions, so learners sometimes treat them as interchangeable.
They aren’t.
Underwent is simple past:
The company underwent restructuring in 2023.
Had undergone is past perfect:
The company had undergone restructuring before the new CEO arrived.
The second sentence establishes a relationship between two past events.
Think of it as a timeline:
Restructuring → New CEO arrives
Because restructuring occurred first, having undergone makes that sequence explicit.
However, don’t add past perfect simply because a sentence contains two past events. Use it when the earlier event needs to be clearly positioned before another past reference point.
Common Mistakes With “Undergo”
“I Have Underwent”
This is one of the most common errors.
Incorrect:
I have undergone several changes.
Correct:
I have undergone several changes.
Why? Have required the past participle here.
The pattern is:
have + past participle
Therefore:
have undergone
not:
have underwent
“She Undergone Surgery”
This sentence is missing the auxiliary verb needed for the intended perfect construction.
Incorrect:
She underwent surgery.
You could correct it in two different ways depending on the intended tense:
Simple past:
She underwent surgery.
Present perfect:
She has undergone surgery.
The missing auxiliary changes the entire grammatical structure.
“They Did Underwent”
Afterwards, use the base form of the verb.
Incorrect:
They underwent the procedure.
Correct:
They did undergo the procedure.
The rule applies to other verbs too:
- Did he go?
- Did she take it?
- Did they undergo testing?
Not:
- Did he go?
- Did she take it?
- Did they undergo testing?
“He Had Underwent”
Afterwards, use the past participle.
Incorrect:
He had undergone treatment.
Correct:
He had undergone treatment.
The pattern is:
had + past participle
Therefore:
had undergone
“She Has Underwent”
This mistake follows the same rule.
Incorrect:
She has undergone several procedures.
Correct:
She has undergone several procedures.
Remember that it does not pair with the simple past form undergone.
How to Choose Between Underwent and Undergone
When you’re unsure, look at the words around the verb.
| Sentence structure | Correct form | Example |
| Subject + ___ + object | underwent | She underwent surgery. |
| Subject + has + ___ | undergone | She has undergone surgery. |
| Subject + have + ___ | undergone | They have undergone testing. |
| Subject + had + ___ | undergone | They had undergone testing. |
| Subject + did + ___ | undergo | They did undergo testing. |
| Subject + is/are + ___ | undergoing | They are undergoing testing. |
The Three-Question Grammar Check
When writing undergo, ask:
Is this a simple past?
Use underwent.
Does the sentence contain has, have, or had?
Use undergone.
Does the sentence contain did?
Use undergo.
For example:
She ___ surgery last year.
Simple past? Yes.
She underwent surgery last year.
Now:
She has ___ surgery.
Present perfect? Yes.
She has undergone surgery.
And:
She did ___ surgery?
After that, use the base form.
She did undergo surgery.
Underwent or Undergone: Examples in Different Contexts
The verb undergo isn’t limited to medical situations. English speakers use it for many kinds of processes and changes.
Medical Context
Medical writing is used frequently because patients experience procedures, treatments, tests, and operations.
Examples:
- The patient underwent surgery yesterday.
- She has undergone several tests.
- He will undergo treatment next month.
- The patient is undergoing chemotherapy.
- They had undergone extensive rehabilitation before returning home.
Cambridge specifically gives medical examples involving surgery, examinations, and reconstructive treatment.
Business and Workplace Context
Businesses can also undergo changes.
Examples:
- The company underwent restructuring last year.
- The organization has undergone significant changes.
- Employees are undergoing additional training.
- The department will undergo a complete review.
- The business had undergone several transformations before the merger.
Here, undergo emphasizes a process of change rather than simply saying that something “changed.”
Science and Technology
Scientific and technical writing also relies on the verb.
Examples:
- The samples underwent laboratory testing.
- The device has undergone extensive evaluation.
- The material is undergoing further analysis.
- The system underwent several modifications.
- The prototype had undergone safety testing before release.
Oxford specifically lists tests, trials, and repairs among common uses of undergo.
General Everyday Context
You can also use undergo for broader experiences.
Examples:
- She underwent a major transformation.
- The neighborhood has undergone dramatic changes.
- He underwent intensive training.
- The project underwent several revisions.
- The plan has undergone considerable changes.
“Undergo” vs. “Experience”: Are They Interchangeable?
Sometimes, but not always.
Experience is a broad word. It can describe almost anything a person encounters.
Undergo tends to emphasize a process, treatment, change, test, or difficult experience.
Compare:
She experienced major changes.
She underwent major changes.
Both can work. However, underwent gives the sentence a more formal and process-oriented feel.
The distinction becomes even clearer with procedures:
The patient underwent surgery.
While experienced surgery is technically understandable, it doesn’t sound natural in standard English.
The same principle applies to:
- undergo treatment
- undergo testing
- undergo surgery
- undergo training
- undergo repairs
- undergo a transformation
These collocations are especially common in formal and technical contexts. Oxford’s dictionary examples and collocations support this pattern.
Is “Underwent” Always Followed by an Object?
Undergo is normally a transitive verb, which means it usually takes an object.
For example:
She underwent surgery.
Here:
- She = subject
- underwent = verb
- surgery = object
Common combinations include:
- undergo surgery
- undergo treatment
- undergo testing
- undergo training
- undergo repairs
- undergo changes
- undergo a transformation
- undergo an examination
- undergo a procedure
Oxford describes undergo as a verb that takes an object and gives examples such as undergoing tests, trials, and repairs.
This is why sentences such as “She underwent” often feel incomplete unless the context makes the object obvious.
Pronunciation of Underwent and Undergone
In American English, underwent is pronounced with the stressed syllable on went, while undergone has the stress on the final syllable.
Cambridge gives the American pronunciations as approximately:
- underwent: /ˌʌn.dərˈwent/
- undergone: /ˌʌn.dərˈɡɔn/ or /ˌʌn.dərˈɡɑn/
The spelling can make these forms look more closely related than they sound.
The important point isn’t simply memorizing pronunciation. You should also recognize the grammatical difference when you hear these forms in conversation.
Undergo: Origin and Word History
The verb undergo has a long history in English. Oxford traces it to Old English undergān, showing that the word has roots much older than its modern grammatical forms suggest.
Its modern forms remain irregular:
undergo → underwent → undergone
That irregular pattern reflects the historical development of English verbs. Not every verb follows the predictable -ed pattern, especially older verbs whose forms developed through earlier stages of the language.
For practical writing, however, you don’t need to memorize the entire history. The useful takeaway is simple: underwent and undergone aren’t interchangeable versions of the same past form.
Underwent or Undergone? Quick Grammar Reference
Keep this table handy when you’re editing an email, article, report, or academic paper.
| If your sentence contains… | Use | Example |
| A completed past event | underwent | She underwent treatment. |
| has | undergone | She has undergone treatment. |
| have | undergone | They have undergone treatment. |
| had | undergone | They had undergone treatment. |
| did | undergo | They did undergo treatment. |
| is/are/was/were + ongoing action | undergoing | She is undergoing treatment. |
A Useful Memory Trick
Think of the three main forms as a small chain:
UNDERGO → UNDERWENT → UNDERGONE
Then attach the common helpers:
- did → undergo
- simple past → underwent
- has/have → undergone
- had → undergone
- is/are/was/were → undergoing
That pattern is much easier to remember than trying to memorize isolated examples.
Case Study: Fixing a Common Grammar Error
Imagine someone writes this sentence in a business report:
“The company has undergone several changes since 2022.”
At first glance, the sentence looks reasonable. The problem is the verb form.
The word has signals a perfect construction. Therefore, the following verb must be the past participle.
The correction is:
“The company has undergone several changes since 2022.”
Now consider a different sentence:
“The company underwent several changes in 2022.”
This sentence is also correct because it uses the simple past and identifies a completed period.
The distinction can be summarized like this:
| Original idea | Correct sentence | Why |
| Past event in 2022 | The company underwent changes in 2022. | Simple past |
| Past event connected to now | The company has undergone changes since 2022. | Present perfect |
| Earlier past event | The company had undergone changes before the merger. | Past perfect |
This small change in verb form can make formal writing noticeably more accurate.
Practice: Underwent or Undergone?
Choose the correct form in each sentence.
Fill in the Blanks
- The patient ______ surgery last Friday.
- The patient has ______ surgery.
- The company ______ major restructuring in 2024.
- The company has ______ major restructuring.
- They had ______ extensive training before the test.
- Did the equipment ______ safety testing?
- The equipment is ______ further testing.
- She has ______ several changes recently.
- He ______ treatment two years ago.
- The building had ______ extensive repairs before reopening.
Answers
- underwent
- undergone
- underwent
- undergone
- undergone
- undergo
- undergoing
- undergone
- underwent
- undergone
The pattern becomes clear once you identify the auxiliary verb and tense.
FAQs
Is “underwent” the past tense of “undergo”?
Yes. Underwent is the simple past tense of undergo. For example, “She underwent surgery last year.”
Is “undergone” the past tense of “undergo”?
No. Undergone is the past participle of undergo. It usually works with an auxiliary verb such as has, have, or had.
What is the difference between “underwent” and “undergone”?
Underwent is used as the simple past form, while undergone is the past participle. You can say “He underwent treatment” or “He has undergone treatment.”
Is “has undergone” correct?
No. The correct form is “has undergone.” The verb has requires the past participle, so undergone must follow it.
Is “has undergone” correct?
Yes. Has undergone is the present perfect form of undergo. For example, “The building has undergone extensive repairs.”
Is “had undergone” correct?
No. The correct construction is “had undergone.” Because had forms the past perfect, it must be followed by the past participle.
Can I say “did underwent”?
No. Afterwards, use the base form of the verb. Therefore, the correct expression is “did undergo,” not “did underwent.”
What is the correct form: “She underwent surgery” or “She underwent surgery”?
“She underwent surgery” is correct when you mean the simple past. “She has undergone surgery” is correct when you use the present perfect.
What are the three main forms of “undergo”?
The three principal forms are undergo, underwent, and undergone. The pattern is:
undergo → underwent → undergone
How can I remember when to use “underwent” and “undergone”?
Use underwent for the simple past, especially when referring to a completed past event. Use undergone after has, have, or had. After I did, I used to undergo.
Conclusion
The difference between underwent and undergone comes down to their grammatical roles. Underwent is the simple past tense of undergo, so you use it for a completed action or experience in the past: “The patient underwent surgery last year.” Undergone, however, is the past participle, which normally needs an auxiliary verb: “The patient has undergone surgery.” The complete verb pattern is undergo → underwent → undergone.
When you’re deciding which form to use, look at the structure around the verb. If you’re describing a straightforward past event, choose underwent. If the sentence contains has, have, or had, choose undergone. If it contains did, use the base form undergo. Once you recognize these patterns, choosing between underwent and undergone becomes quick, clear, and much less confusing.
