Background: To assess hormonal contraceptive use and response to antiretroviral therapy (ART) as measured by changes in HIV-1 RNA viral load (VL) and CD4+cell counts in HIV positive female adolescents on ART. Material and Methods: This study used prospective longitudinal data from the REACH cohort to compare the response to ART in adolescent females using hormonal contraception to the response to ART in adolescent females not using hormonal contraception. Outcome measures were VL and CD4+T cell counts assessed every 3 months. The association between hormonal contraception exposure and the response to ARTwasassessed using repeated measures multivariate analysis while adjusting for additional covariates. Results: The majority of participants were African American (73%). Median baseline age was 17 years (IQR 16 - 18). VL of ART users decreased over time in both hormonal contraception users (-0.0152 log copies/ml per day) and non-users (-0.0154 log copies/ml per day). However, the decrease was slightly lower (1.2×10-3, 95%CI: 6.2×10-5-2.4×10-3copies/ml log VL per day, p-value = 0.03) among hormonal contraceptive users. Conclusions: This study shows a significant association between hormonal contraception use and a diminished response to ART. However, the impact of hormonal contraception on HIV-1 acquisition, progression, and treatment is still not clear. © 2011 Published by Elsevier Urban & Partner Sp. z.o.o. on behalf of Polish AIDS Research Society.