Depot medroxyprogesterone acetate (DMPA) use among HIV-1-infected women may increase transmission by increasing plasma and genital HIV-1 RNA shedding. We investigated associations between DMPA use and HIV-1 RNA in plasma and cervical secretions. One hundred two women initiated antiretroviral therapy, contributing 925 follow-up visits over a median of 34 months. Compared with visits with no hormonal contraception exposure, DMPA exposure did not increase detection of plasma (adjusted odds ratio: 0.81, 95% confidence interval: 0.47 to 1.39) or cervical HIV-1 RNA (adjusted odds ratio: 1.41, 95% confidence interval: 0.54 to 3.67). Our results suggest that DMPA is unlikely to increase infectivity in HIV-positive women who are adherent to effective antiretroviral therapy.