PURPOSE The use of medical students as standardized patients in a performance assessment of pain evaluation was studied. METHODS Fifty-two pairs of second-year medical students participated. One student portrayed a patient presenting with cancer pain and was interviewed by the other medical student. The student-patient then rated the interview using a checklist of pain assessment and general interviewing skills. The interviews were audiotaped and also rated independently. RESULTS Based on student-patient ratings, 36 (69%) students demonstrated 9 or more of the 11 pain-specific checklist items, compared to 34 (65%) students according to the trained rater. Highly specific pain-related items had higher agreement than broader interviewing skill items. There would be differences in the summary assessments of students depending on which rating data were used. DISCUSSION Medical students represent a readily accessible resource as patients for clinical simulations. Students tended to overestimate the performance of fellow students, but acting as a standardized patient had educational value, and can be used to extend simulated patient encounters within the curriculum. Further investigation is needed to improve the reliability of the feedback provided by student-patients.