An interactive computerized utilization review system for psychiatric inpatient care was developed and tested on a 30-bed acute admission ward, where staff were trained in its use. The program permitted staff to review clinical decisions affecting length of stay and to receive immediate feedback on the cost and revenue for each case. The impact of the system was evaluated by comparing the length of stay of patients on the study unit with that of patients on a similar unit where the system was not in use, and also by comparing the length of stay for both units before and after the system was implemented. The findings showed that the length of stay on the study unit was significantly reduced after the system's implementation, and that it was well accepted by the staff. Six-month follow-up data showed no increase in symptomatology for the study patients compared with the control group.