The official USMLE sample test questions—known across medical schools as the Free 120—are published directly by USMLE on the official interactive testing experience for USMLE Step 1, USMLE Step 2 CK, and USMLE Step 3. Because they run inside the same testing interface used on exam day, they are the single best rehearsal for screen layout, laboratory reference values, audio and multimedia items, and block transitions.
What the Free 120 includes
Each Step exam has its own official web-based sample item set and downloadable PDF booklet on usmle.org. The interactive web version lets you practice highlighting, striking out options, searching the lab table, and pacing through blocks under the current 30-minute block structure. For Step 3, the official sample materials also include interactive computer-based case simulations (CCS) so you can rehearse entering orders and advancing simulated clock time before test day.
Taking the Free 120 online vs. at a Prometric test center
You can complete the sample items for free from your own computer at any time, or you can apply for an optional practice session at a Prometric test center once you hold a valid scheduling permit. Taking the practice session at your actual testing center lets you rehearse the commute, check-in procedure, locker rules, and break-time routine under realistic conditions.
When to schedule the Free 120 in your study plan
- Five to seven days before test day: Take the Free 120 in timed blocks after your final NBME self-assessment so you have enough time to review every missed concept without burning out right before the exam.
- Pair it with your final pass of high-yield topics: Cross-check any missed question stems against the USMLE content outline and passing standards.
- Review every option: Official sample items do not include written explanations inside the testing software, so trace why each distractor is wrong using First Aid or your question bank notes.