An open, randomized, comparative study of intravenous ciprofloxacin versus gentamicin and clindamycin was performed on women with postpartum endometritis. Ciprofloxacin alone successfully eradicated the infections in 35 of 49 patients (71%), while the combination of gentamicin/clindamycin cured 41 of 48 (85%) (P = .15). The microbiology and antibiotic sensitivity of the endometrial isolates confirmed the poor activity of ciprofloxacin against anaerobic bacteria and less-than-optimal activity against Streptococcus faecalis. Ciprofloxacin, when used alone, may not be suitable for the treatment of postpartum endometritis.