A new single-antibiotic combination of ticarcillin and clavulanic acid was compared with the standard two-drug regimen of clindamycin and gentamicin in the treatment of post-cesarean endomyometritis. The regimens were as follows: 3 g of ticarcillin plus 100 mg of clavulanic acid intravenously every four hours; or 600 mg of clindamycin intravenously every six hours plus 3 to 5 mg/kg per day of gentamicin intramuscularly. The prospective randomized schedule was calculated such that half the patients were assigned to each treatment group. The diagnosis of endomyometritis was based upon an elevated oral temperature of 100.4 degrees F or higher on any two occasions, excluding the first 24 hours after delivery, uterine tenderness, and the absence of other foci of infection. Lochial discharge was foul in most cases. Forty-seven patients were treated. Treatment was successful in all patients who received clindamycin and gentamicin; ticarcillin plus clavulanic acid failed in two of 23 (9 percent) patients. Patients in whom treatment failed did not appear to be different from those in whom treatment was successful on demographic variables or in terms of risk factors for endomyometritis. The difference between the treatment failure rates was not statistically significant. This study suggests that the single-drug combination of ticarcillin plus clavulanic acid is effective in the treatment of post-cesarean endomyometritis when compared with the standard regimen of clindamycin and gentamicin.