This study compares the demographic features and hospital course of all 472 patients discharged against medical advice from the general medicine service of an urban teaching hospital between 1984 and 1995 and 1,113 control patients discharged with physician approval. In the multivariate analysis, younger age (odds ratio [OR] 0.97 per year; 95% confidence interval [CI] 0.96, 0.98), male gender (OR 1.9; 95% CI 1.4, 2.4), lack of health insurance (OR 2.0; 95% CI 1.3, 3.1), Medicaid applicant or recipient status (OR 2.2; 95% CI 1.6, 3.1), admission through the emergency department (OR 2.2; 95% CI 1.4, 3.5), and lack of a personal attending physician at the time of admission (OR 2.1; 95% CI 1.6, 2.8) increased the odds of discharge against medical advice. Fifty-four percent of patients who left against medical advice were readmitted to the hospital during the study period; 98% were then discharged with physician approval. Patients who left the hospital against medical advice included many disadvantaged individuals without ongoing primary care.