Nineteen patients who left a short-term psychiatric crisis unit against medical advice were compared with 109 patients who received a regular discharge during a six-month period. Demographic, historic, assessment, and diagnostic variables of both groups were examined. Results indicated that patients diagnosed as having personality or substance use disorders and patients judged abnormal on a mental status examination were more likely to be AMA patients. However, AMA patients indicated fewer social problems as rated on Linn's Social Dysfunction Scale. It was concluded that diagnostic variables best differentiated patients leaving the treatment unit against medical advice from those who completed treatment.