The prevalence of hypothesized risk factors of drug impairment is estimated and correlated with drug use in random samples of physicians and medical students. Substantial percentages of both physicians and medical students reported access to drugs, family histories of substance abuse, stress at work and home, emotional problems, and sensation seeking. Each of these factors correlated with drug use in physicians or medical students, and analysis suggested that in most cases the hypothesized risk factors were more likely to be causes rather than consequences of drug use.