Sixty-three women with abdominal pain and adnexal tenderness were enrolled in a study of ambulatory treatment of acute pelvic inflammatory disease. Treatment consisted of 2 g of cefoxitin intramuscularly and 1 g of probenecid orally, followed by doxycycline, 100 mg by mouth twice daily for 14 days. Patients were stratified into groups indicating whether pelvic inflammatory disease was probable, possible, or unlikely, based upon endometrial biopsy and clinical criteria. Among 52 women who were evaluated, Chlamydia trachomatis and/or Neisseria gonorrhoeae were initially recovered from 16 (67%) of 24 with probable pelvic inflammatory disease, three (33%) of 11 with possible pelvic inflammatory disease, and three (18%) of 17 in whom pelvic inflammatory disease was considered unlikely. Of the 24 patients with probable pelvic inflammatory disease, 22 (92%) were clinically cured or improved. Of 22 patients initially infected with C trachomatis and/or N gonorrhoeae, 20 were culture-negative for both organisms after therapy. Both microbiologic failures had been reexposed. This study suggests that the combination of cefoxitin and doxycycline is effective for ambulatory treatment of pelvic inflammatory disease.