Imipenem is a new broad-spectrum beta-lactam antibiotic, which when administered with cilastatin may be a suitable alternative to the combination of an aminoglycoside and either clindamycin or a nitroimidazole as therapy for intraabdominal infections. The clinical and microbiologic results for 164 assessable patients given imipenem/cilastatin for intraabdominal infections are reported. Only three of 416 bacterial strains isolated prior to therapy from intraabdominal infection sites were resistant to imipenem (one of Staphylococcus epidermidis, one of Morganella morganii, and one of the Fusobacterium varium). Resistance acquired during treatment was reported in four cases: for three strains of Pseudomonas aeruginosa and for one strain of Proteus mirabilis. Of 412 strains susceptible to imipenem prior to therapy, 359 were eradicated during treatment. The frequency of clinical cure or improvement was 91%. Imipenem/cilastatin seems to be a useful alternative to the combination of an aminoglycoside with either clindamycin or a nitroimidazole.