A multicentre open trial was conducted in 31 centres to evaluate the therapeutic and ecological impact of imipenem-cilastatin on patients admitted to infectious pathology departments. Two-hundred patients (mean age: 58 +/- 19.4 years) were included in the study. The predominant infections were septicaemia, severe urinary tract infections and lower respiratory tract infections. Most of the patients treated (188/200) had associated severity factors. The acute infectious episode had been present for 9.3 +/- 12.2 days before the drug was prescribed. In the majority of patients the infection was hospital-acquired. Two-hundred and fifteen out of the 298 initial bacterial isolates were Gram-negative bacilli. Imipenem-cilastatin was administered alone in 74.5 per cent of the patients during 14.1 days on average in doses of 30 mg/kg/day. The drug was given as first-choice treatment in 60 per cent of the cases and after failure of another antibiotic therapy in 40 per cent. Clinical cure was obtained in 180 of the 198 assessable patients. Among therapeutic failures, 4 were due to the emergence during treatment of an imipenem-resistant Pseudomonas aeruginosa, but 30 of the 42 strains of Pseudomonas isolated before treatment were eradicated. The therapeutic success rates were 100 per cent in intra-abdominal infections, 94 per cent in septicaemias, 97 per cent in urinary tract infections and 82 per cent in lower respiratory tract infections, this last figure being one of the highest recorded in clinical trials. Frequent colonization or superinfection were not encountered in this study. The incidence of phlebitis at the site of injection was 14 per cent.