Imipenem/cilastatin sodium (MK-0787/MK-0791) was studied for its penetration into the adnexa uteri and uterine tissue, as well as for its clinical efficacy in the treatment of patients with obstetric and gynecologic infections. The following results were obtained. When 500 mg/500 mg of MK-0787/MK-0791 was administered by an intravenous drip infusion, peak levels of MK-0787 in tissues of adnexa uteri and uterus ranged from 14.6 micrograms/g to 25.8 micrograms/g, Tmax ranged from 0.55 hour to 0.98 hour, and the AUC ranged from 25.6 micrograms X hr/g to 45.2 micrograms X hr/g. Thus, the penetration of the drug into these tissues was good. Clinical efficacy of MK-0787 was evaluated in 30 patients in the field of obstetrics and gynecology. The clinical efficacy was excellent or good in all patients. Bacteriological effects of MK-0787/MK-0791 were very good, and 90% of the organisms detected before the treatment were eradicated. The antimicrobial activity of MK-0787 was tested against pathogens isolated before, during and after the treatment. Mean MIC80 values of MK-0787 were 0.39-0.78 micrograms/ml against all Gram-positive bacteria, 0.20-0.39 micrograms/ml against all Gram-negative bacteria, and less than or equal to 0.10-0.20 micrograms/ml against all anaerobic bacteria. The antimicrobial activity of MK-0787 appeared very good. No side effects or abnormal laboratory findings were observed except a slight elevation of S-GPT in 1 patient.