As stated in the USMLE Bulletin of Information, the level of proficiency required to meet the recommended minimum passing level for each USMLE Step examination is reviewed periodically and may be adjusted at any time. Notice of such review and any adjustments are posted on the USMLE website.
Every three to four years the Step Committees are asked to complete an in-depth review of standards, and they may schedule more frequent reviews.
At its June 2010 meeting, the Step 2 Committee conducted a review for USMLE Step 2 Clinical Knowledge (CK). As a result of its review, the Step 2 Committee decided to raise the three-digit score recommended to pass Step 2 CK from 184 to 189. As previously reported, at that time the Committee decided to closely monitor the effects of this decision on examinees and schools, and to examine trends in performance on an annual basis.
The Committee will review the three-digit score recommended to pass Step 2 CK at its June 2012 meeting. If the Committee determines that a change is appropriate, the new recommended minimum passing score will become effective for all examinees who take a Step 2 CK examination on or after July 1, 2012.
Reference: usmle.org website