On 26 October 1974, 3356 diplomates of the American Board of Internal Medicine (ABIM) took a 1-day written examination for recertification consisting of multiple-choice, matching, and true-false questions derived from the American College of Physicians' Medical Knowledge Self-Assessment Program III and the ABIM Certifying Examination pool. The passing score was set by using a normative standard applied to a reference group of internists practicing general internal medicine who had had 2 or more years of residency training completed between the years 1949 and 1958. The passing score represented approximately 63% correct answers. The failure rate for the total number of examinees was 4.3%. Mean score of examinees showed an inverse relation with age but relatively slight differences when analyzed according to the degree of subspecialization, practice setting, hospital affiliation, or size of patient community.