Thirty-six women with suspected pelvic inflammatory disease were examined by laparoscopy and endometrial biopsy. Acute salpingitis was diagnosed by laparoscopy in 22. Among women with evaluable biopsy samples, plasma cell endometritis was present in 14 of 20 with acute salpingitis and in 1 of 13 without acute salpingitis (p less than 0.001). Chlamydia trachomatis, Neisseria gonorrhoeae, or both were identified in the endometrium or fallopian tubes in 11 of 14 women with both salpingitis and endometritis, in 2 of 9 with salpingitis or endometritis alone, and in 0 of 13 without salpingitis or endometritis (p less than 0.0001). Anaerobic or facultative bacteria or mycoplasmas were isolated from tubes or peritoneum from 9 of 14 women with both salpingitis and endometritis, 2 of 9 with salpingitis or endometritis alone, and 3 of 13 without salpingitis or endometritis. Therapy with clindamycin plus tobramycin produced an adequate short-term clinical response in 16 of 19 patients, although patients with severe salpingitis at laparoscopy responded slowly.