A survey of alcohol and other drug-use patterns of 300 second- and third-year students at a mid-Atlantic private medical school was undertaken in 1987. Two hundred sixty-three (88%) of the medical students surveyed completed the anonymous questionnaire. Tobacco use decreased from 11% before to 4% during medical school. Before entry into medical school, 21% of the respondents had smoked marijuana 10 times or more, usually at least monthly, while 9% had smoked marijuana 10 times or more during medical school. Six percent had smoked marijuana daily in high school or college, while 1% smoked marijuana daily in medical school. Few students who used cocaine before medical school abstained from it during medical school. Cocaine was used by 17% of the respondents before and during medical school. Frequent use of cocaine (greater than 10 times) during medical school, reported by 5% of the students, was directly related to excessive alcohol intake, tobacco dependence, frequent use of marijuana before and during medical school, and medical and behavioral problems related to alcohol and other drug use. Less than 25% of medical schools have a formal policy aimed at identifying impaired students, and only 12% have formal treatment protocols for helping impaired students. We propose that all medical schools initiate programs to diagnose alcohol and other drug-abuse problems in medical student candidates and in the students themselves, and that intervention for any alcohol or other drug problem be encouraged and supported by formal medical school policies designed to help the impaired student.