The clinical efficacy and safety of imipenem/cilastatin in the empirical treatment of adult non-immunocompromised patients with severe bacterial septicemia was studied in a prospective and open trial. The dosage of imipenem/cilastatin was 500 mg q 6 h. Of 58 patients included, 41 were evaluable for efficacy. In those patients, 35 had chronic underlying diseases and the foci of bacteremia were identified in 37; the most common ones being cardiovascular, urologic or intraabdominal infections. All isolated organisms were sensitive to imipenem with an MIC for 90% of the strains of 1 mg/l. Imipenem/cilastatin treatment resulted in rapid control of the infections in 39 of the 41 evaluable patients (95.5%). In the remaining two patients treatment had to be prematurely discontinued due to adverse effects. The causative bacterial strains were eradicated from blood in all patients who received more than one day of imipenem/cilastatin treatment but persisted sensitive to imipenem in peripheral foci in five patients (17%). Clinical and laboratory adverse reactions were noted in seven patients. In conclusion, imipenem/cilastatin was a well tolerated and effective empirical drug for treatment of septicemia.