A multicentre, non-comparative study was performed to evaluate the clinical efficacy and safety of imipenem/cilastatin given iv to 53 seriously ill patients with severe bacterial infections, including 16 episodes of UTI, 12 pleuropulmonary, eight intra-abdominal, seven osteoarticular, and two soft tissue infections, three episodes of catheter related sepsis, two primary bacteraemias, one case of endocarditis, one of endophthalmitis, and one of disseminated gonococcal infection. Twenty-five patients were bacteraemic. The overall rate of clinical response was 94% of treated episodes; three cases failed to respond. Adverse reactions were mild and comparable with those reported with other beta-lactams. No patient had clinical superinfection; colonization occurred in seven patients. Imipenem is effective and safe as a single drug therapy for a wide range of infections in seriously ill patients.