The ability of medical students to recognize heart murmurs is poor (20%), and does not improve with subsequent years of training. A teaching method to improve this skill would be useful. To determine whether intensive repetition of four basic cardiac murmurs improves auscultatory proficiency in medical students. Controlled intervention study. Fifty-one second-year medical students in an east coast medical school. Subjects were classified into three groups: (1) a monitored group, who listened to 500 repetitions of each murmur in a monitored setting, (2) an unmonitored group, who listened to 500 repetitions of each murmur in an unmonitored setting, and (3) a control group. All three groups were tested using a pretest and posttest methodology. The 20 subjects in the monitored group improved from 13.5 +/- 9.8 to 85 +/- 17.6% following the intervention (mean +/- SD). Similarly, 21 students in the unmonitored group improved from 20.9 +/- 10.9 to 86.1 +/- 15.6%. Ten control students showed no significant improvement (24 +/- 21.7 to 32 +/- 22.5%). The differences between the two intervention groups and the control subjects was significant at p < 0.001 by analysis of variance. Five hundred repetitions of four basic cardiac murmurs significantly improved auscultatory proficiency in recognizing basic cardiac murmurs by medical students. These results suggest that cardiac auscultation is, in part, a technical skill.