The relationship between mental rehearsal and facial identification accuracy was explored in two experiments involving either a staged classroom event or a video scenario. The results suggest that when subjects rehearsed immediately following an event, compared to subjects in non-rehearsal conditions, identification accuracy was increased when the target face was unchanged in appearance but was reduced when the face was changed slightly in appearance from viewing to test. However, when rehearsal of the event was delayed 10 minutes, identification accuracy was improved even when the face had changed in appearance. Immediate rehearsal, in contrast, led to a reduction in identification performance. In short, in some circumstances the gains in specific memory brought about by mental rehearsal serve to reduce than improve identification accuracy. The relevance of these findings to memory theory and everyday eyewitness testimony is discussed.