Physicians will be subject to periodic reexamination in the course of their professional careers. There is an urgent need to determine correlations between test results on examinations now being used and the actual competence of physicians in their clinical practice situations. The authors review several facets of the present status of testing: the internal reliability of tests, their content, and various testing methodologies. Data in all of these areas illustrate the difficulties involved in testing clinical competence and emphasize the need for research and action.