Among 830 women attending a clinic for sexually transmitted disease, Chlamydia trachomatis was isolated from 180 (22%) and Neisseria gonorrhoeae from 84 (10%). Retrospective analysis showed that 43 of the women were given outpatient treatment for acute pelvic inflammatory disease because they had low abdominal pain, deep dyspareunia, or unusual vaginal bleeding, or all of these, for less than 2 months in association with cervical motion or adnexal tenderness, or both. None had adnexal masses. C. trachomatis was isolated from 22 and N. gonorrhoeae from 15 of this subgroup of 43 women. This presentation of pelvic inflammatory disease occurred in 10 of the 37 women in the whole study with both C. trachomatis and N. gonorrhoeae, 12 of 143 women with C. trachomatis alone, five of 47 women with N. gonorrhoeae alone, and 16 of 603 women with neither organism. Thus, in North America, C. trachomatis is associated with a syndrome usually diagnosed as mild pelvic inflammatory disease and managed on an outpatient basis.