A hospital-based case-control study was conducted in two hospitals in Bangkok, Thailand, and in one hospital each in Chiang Mai, Thailand, Mexico City, Mexico and Nairobi, Kenya. One purpose of this study was to determine whether the long-acting progestational contraceptive, depot-medroxyprogesterone acetate (DMPA), alters risk of invasive cervical carcinomas with adenomatous histological features. Information on prior use of DMPA, screening for cervical cancer, and the suspected risk factors for this disease was ascertained from interviews of 239 women with adenocarcinomas and 85 women with adenosquamous carcinomas, as well of from a large pool of controls, 2534 of whom were matched to the cases included in this report. For selected subsets of these women, a smoking history was also elicited, blood specimens were collected for measurement of antibodies against herpes simplex and cytomegalovirus, and information on sexual behavior was obtained from interviews of their husbands. The relative risk (and 95% confidence interval) of adenomatous cervical carcinomas in women who ever used DMPA was estimated to be 0.75 (0.51, 1.11). No trends in risk were observed with duration of DMPA use, times since first or last use, or age at first use. The results provide reassurance that use of DMPA for over four years does not enhance risk of adenomatous cervical carcinomas, and risk is not increased after a potential latent period of over 12 years since initial exposure.