Necessary modifications to the test item pool of USMLE Step 1, will cause a delay in reporting for some examinees score reports beginning the week of May 13th.  The target date for reporting Step 1 scores for most examinees testing the week of May 13th through late June will be Wednesday, July 10, 2013.

Examinees are advised to take Step 1 no later than May 10, 2013 if they require score reports earlier.

Via USMLE News