Among women attending family planning clinics in Nairobi, Kenya, the HIV-seroprevalence rates for different contraceptive methods were: depomedroxyprogesterone acetate (DMPA) 431/3279 (13.1%), combination oral contraceptive pill 114/1073 (10.6%), and progesterone-only contraceptive pill (POCP) 45/741 (6.1%). After adjusting for age, marital status, and parity, women using the POCP had a lower HIV seroprevalence (adjusted odds ratio 0.5, 95% confidence interval 0.3-0.7) than women using DMPA. This association was most pronounced among POCP users of lower parity.