Development and use of a drug-use evaluation (DUE) program for hospital and outpatient facilities of a health-maintenance organization (HMO) are described. A full-time pharmacist coordinates the DUE program. Primary components of the DUE program are (1) establishment and use of drug therapy management protocols, (2) periodic review and evaluation of drug-use statistics by the pharmacy and therapeutics (P&T) committee, (3) monitoring of pharmacist interventions, and (4) evaluation of specific drug use within individual medical staff departments. Information from all DUE activities is channeled through the P&T committee and linked to the HMO's overall quality assurance program. The DUE program has the support of the HMO physicians. It has enhanced the quality of drug use and identified opportunities to further improve the quality of patient care. In surveys by the Joint Commission on Accreditation of Healthcare Organizations, the HMO facilities have received no recommendations. Pharmacists and physicians have cooperated to develop a comprehensive DUE program for an HMO.