We investigated the frequency of clinically defined upper genital tract infection (UGTI) and its relation to sexually transmitted diseases and other risk factors among 1,013 women initially studied while in labor at a Nairobi, Kenya maternity hospital. Women were enrolled during labor and followed up at seven days and one month postpartum. Cultures for Neisseria gonorrhoeae and Chlamydia trachomatis were done at enrollment and at day 7. The prevalence of gonococcal and chlamydial infections was 6.7% and 20.8%, respectively. The overall prevalence of UGTI was 20.3%. The development of UGTI was significantly correlated with gonococcal infection (odds ratio, 4.4; P less than .0001), chlamydial infection (odds ratio, 1.7; P less than .02), presence of ophthalmia neonatorum (odds ratio, 2.6; P less than .0001), labor greater than 12 hr (odds ratio, 1.8; P less than .01), and area of residence (odds ratio, 1.5; P less than .05). Postpartum UGTI, an enormous public health problem in Nairobi, would be partially susceptible to antenatal intervention programs focusing on sexually transmitted diseases.