The American Board of Internal Medicine has requested that residency program directors certify the clinical competence of their candidates. The clinical evaluation exercise (CEX) is one component of the overall certification process. During 1980-1982, 120 residents at the University of Michigan Hospitals participated in a CEX. The results show recurrent inadequacies among the residents in eliciting the social and family histories and performing the mental status and neurologic examinations. The ability to elicit a complete medical history correlated (p less than .01) with communication skills. In three of four specific organ examinations, the ability to perform a technically correct and complete physical examination correlated with the accuracy of the residents' findings (p less than .05). Separate evaluations by senior faculty members generally did not correlate with the residents' performance on the CEX. Analysis of the program described here showed that it requires considerable faculty time, requires training of evaluators to develop interrater reliability, and raises questions as to the validity of the CEX. As national certification boards integrate a formal clinical component into the certification process, such problems need to be addressed and rectified.