One hundred thirty-two physicians who successfully completed advanced cardiac life support (ACLS) training were randomly placed in a control group or one of two groups receiving interventions designed to provide reinforcement of previously mastered knowledge and skills. These interventions included mailed periodic reprints (group 1) or quarterly patient management problems (group 2). All physicians were retested for knowledge and skills related to ACLS one year later. Fifty-two (39.4%) could successfully ventilate the mannequin, and 62 (47.0%) could perform cardiac compression adequately. No differences were noted among groups. Significant differences in knowledge were found. The control group initiated appropriate therapy in a mock-arrest situation 52% of the time, while group 1 averaged 75% and group 2 averaged 82%. These results indicate that reinforcement after continuing medical education may enhance knowledge retention, but does not maintain motor skills. Yearly recertification in ACLS skills should be considered, and frequent practice sessions should be encouraged for those physicians who are not active participants in ACLS activities.