Quality controls are becoming an important part of our health care system. A medical audit is one way of evaluating quality of care, and this paper describes the results of an audit conducted to investigate the reasons for a prolonged stay on a psychiatric inpatient unit. The results showed a decrease in the mean length of stay over a five year period, although the figure remained substantially above provincial norms. A review of the hospital charts of a random sample of one in six patients whose hospital stay exceeded 30 days was carried out. It revealed that in 50.0% of cases the reasons were "medically acceptable," in 10.3% the reasons were "medically unacceptable" and in 39.7% the reasons were "social and administrative" and beyond the control of the treating psychiatrist. The implication of these results are discussed.