Imipenem/cilastatin was used for the treatment of 594 bacterial infections in 545 patients at a dosage of 1.5 g/day (n = 283), 2.0 g/day (n = 129), 3.0 g/day (n = 102), or 4 g/day (n = 11). The most common indications for therapy were nosocomial pneumonias followed by intraabdominal postoperative infections, and skin and soft tissue infections. Out of 1171 bacterial strains isolated from 932 patients, seven showed primary resistance to imipenem. The causative agent was eliminated in 87% of the patients. Treatment failed in 24 of the 594 patients. In 35 patients therapy was stopped because of side effects. The most frequent side effect was local irritation at the site of intravenous application.