Three facts about how the USMLE counts your answers should shape the way you work through every block. There is no penalty for a wrong answer. Some questions do not count at all. And you cannot tell which ones those are. None of this is a secret, but students who take it seriously handle the exam more calmly than students who do not.
A wrong answer costs nothing extra
Your score is based on the number of questions you answer correctly. There is no deduction for a wrong answer, so a guess can only help you.
That makes the first rule simple: answer every question. A blank is always wrong. A guess between two plausible options is right about half the time, and even a blind guess has a real chance. There is no situation in which leaving a question blank is the better choice.
This matters most at the end of a block, when time is running out. If you have several questions left and not enough time to read them, put an answer on each one first, then use whatever time remains to read and change them. A block that ends with blank answers has given away marks for nothing.
How to guess well
When you are unsure, a guess can still be informed.
Eliminate what you can. If you can rule out two options with confidence, your odds improve sharply, even if you are not sure between the rest.
Go with your first reasoned choice. If you worked through the question and chose an answer for a reason, changing it later without a new reason is rarely an improvement. Change an answer when you notice something you missed, not because it feels uncomfortable.
Do not spend too long on one question. A question you cannot answer after a reasonable effort is worth a quick guess and a mark for review. The time is better spent on questions you can answer.
Some questions do not count
Each USMLE exam includes pretest questions. These are new items being tried out for future exams, and they do not count toward your score. They appear alongside scored questions, in the same format, and nothing on the screen tells them apart.
The programme uses pretesting to check that new questions perform as intended before they are used for scoring. That is how a large exam keeps a reliable pool of questions. For you, the effect is simply that some of the questions you answer have no bearing on your result.
Do not try to spot them
It is tempting to look for patterns: an oddly worded question, a topic you have never seen, an option list that seems off. Some students convince themselves they can identify pretest items and decide to skip or rush them.
This is a mistake. Pretest questions are written to the same standards as scored ones, and many of them will become scored questions later. A question that feels unusual is far more likely to be a scored question on a topic you know less well than an experimental one. Treating it as unscored is a good way to throw away a point.
What unscored questions are good for
There is one useful way to think about them: as a reason not to panic.
Every exam contains questions that feel strange, unfamiliar or impossible. Some of those may be pretest items, and some will be hard scored questions that most students also miss. Either way, one strange question tells you nothing about how the exam is going.
Students who let a bizarre question shake them often carry that unease into the next several questions, where the real damage happens. A better habit is to answer it, mark it if you want to revisit it, and move on. If it was a pretest item, it did not count. If it was not, most other students found it hard too.
Working within a block
Within a block you can move back and forth between questions, change answers and mark questions to revisit. Once the block ends, either because time runs out or because you end it, you cannot return to it.
That suggests a simple routine. Work through the block in order, answering every question as you go, and mark the ones you would like to revisit. If time remains at the end, go back to the marked ones. If it does not, every question already has an answer.
The 2026 test software divides each exam into more, shorter blocks, so the end of a block arrives more often than it used to. Practise answering everything inside the time limit in blocks of the length you will sit, so the routine is automatic by test day. Most banks let you set block length, whether you use UWorld, AMBOSS or QBankly, and it is worth matching it to the exam rather than leaving the default.
Applying this in practice
Treat every practice block as a rehearsal of these habits. Answer everything, guess sensibly, mark and move on, and never leave a blank when the timer runs out.
When you review afterwards, look at the questions you guessed on as well as the ones you got wrong. A correct guess still points to something you did not know, and flagging guesses as you go makes it easier to come back to them rather than letting a lucky answer hide a gap.
Frequently asked questions
Is there a penalty for guessing on the USMLE?
No. Your score depends on how many questions you answer correctly, and a wrong answer costs nothing beyond the missed point. A blank answer is always wrong, so guessing is always better than leaving a question unanswered.
Are there experimental questions on the USMLE?
Yes. Each exam includes questions being pretested for future use, and they do not count toward your score. They appear alongside scored questions and look identical, so there is no way to tell which ones they are.
Can I go back to a previous block on the USMLE?
No. Within a block you can move between questions, change answers and mark items to revisit, but once a block ends you cannot return to it. Anything left unanswered when the block closes stays unanswered.