This prospective, randomized controlled study compared the efficacy and safety of ciprofloxacin alone versus a conventional two-drug regimen, clindamycin with gentamicin. The study group included 71 patients hospitalized for pelvic infections such as acute (N = 33) and chronic (N = 8) salpingitis, tubo-ovarian abscesses (N = 11), endometritis (N = 9), septic abortion (N = 3), and other categories (N = 7). Twenty-two of 35 patients on ciprofloxacin and 20 of 36 on clindamycin plus gentamicin had culturable pathogens: gonococci in 28, anaerobes in six, chlamydia in four, and associated pathogens in 19. Complete clinical and bacteriologic cure was achieved in 21 of 22 (95%) in the ciprofloxacin group and 19 of 20 (95%) in the clindamycin plus gentamicin group. The mean duration of intravenous/oral ciprofloxacin therapy was 3.7/7.2 days, and it was 3/6.6 days for clindamycin plus gentamicin. Ciprofloxacin, a new quinolone, appears to be safe as a single-drug therapy and was as effective as the combination of clindamycin plus gentamicin for the treatment of severe pelvic infections requiring hospitalization.