Drug abuse is a leading occupational hazard for operating room personnel. Easy access to controlled substances allows drug dependence to develop and flourish. A system that accurately audits the distribution of controlled substances used in the operating room may decrease the onset of drug abuse and make it easier to identify drug addicts. A simple, inexpensive, and reliable system that improves accountability of controlled substances is described in detail. This system involves participation by anesthesiologists, operating room nurses, and pharmacists to accurately record amount and type of drugs dispensed, used, wasted, and returned. Periodic, random, qualitative, and quantitative analyses of drugs returned for wastage are performed. In the first 6 months in which the system was used, 6,336 patients were treated and 7,182 ampules of controlled substances were dispensed. Thirty-seven incident reports describing deviations from the protocol occurred. In each case an explanation for the discrepancy was determined and compliance with the protocol was subsequently improved. No cases of drug diversion were discovered or suspected. The system described is simple and inexpensive to implement and has improved accountability for controlled substance management.