This article describes an imipenem/cilastatin (I/C) target drug program. The program, developed following completion of a drug usage evaluation study, was designed to improve I/C dosing, reduce central nervous system (CNS) adverse effects, and reduce antibiotic costs. Following completion of an inservice education program for the medical and pharmacy professional staffs, ongoing monitoring of I/C usage was accomplished through the pharmacy-based drug-dosing service. Pharmacists evaluated I/C dosage based upon culture/sensitivity results and indicators of renal function. If deemed inappropriate, the pharmacist contacted the prescribing physician with a dosage recommendation. Two hundred ten courses of I/C therapy were prescribed in the nine-month period following implementation of the target drug program; 26 cases (12 percent) required dosage adjustment. The incidence of CNS adverse effects including seizures decreased from 15 to 1 percent (p = 0.0015). A $6033 drug cost avoidance also resulted from pharmacist intervention.