The fever index measured the responses of 102 women with serious pelvic infections who had received either chloramphenicol or clindamycin, in combination with other antibiotics. There was no statistical difference in the number of degree hours in the two populations. Patients with salpingo-oophoritis had significantly more fever than those with a septic abortion. Bacteremia did not delineate a group of women with a markedly elevated febrile response. Within the population with salpingo-oophoritis, neither black women nor women with an intrauterine device in place had significantly more fever, but patients requiring operation had more fever while those with an endocervical culture positive for the gonococcus at the time of admission had the most favorable clinical response. The significance of these findings is discussed.