Patients who leave hospitals against medical advice (AMA) frustrate physicians and may put themselves at medical risk. A case-control study was conducted to characterize the factors associated with AMA discharges from an impatient medical service. Logistic regression analysis indicated that not having a primary care physician and previous AMA discharge were significantly associated with leaving AMA. The patients most often stated that they were leaving because they "felt better" or had personal or financial obligations. However, the patients leaving AMA were more likely to return for care within the next week than were the control patients.