The aim of this study was to evaluate the prevalence of the concomitant use of herbal medicine and anti-retroviral drugs in people living with HIV/AIDs and to evaluate the reasons given by the pati ents for concomitant admini stration of highly active antiretroviral therapy (HAART) with herbal drugs in order to establi sh a possible link between the use of herbal medicines and adherence. A cross sectional study design was utilized via systematic sampling for recruitment of HIV positive individual s receiving their medications in Amuwo-Odofin and Ojo areas in Lagos, Nigeria. Based on the inclusion criteria, 351 HIV positive patients were recruited into the study from the HIV outpatient clinics of two hospital s and had the questionnaires administered to them. 42.7% of the respondents stated that they use herbal medicines. The association for each of the herbal medicines with side effects experienced with the use of ARV s wa s stati sti cally significant upon cross-tabulation and was a major predictor of herbal drug use. The prevalence of herbal drug use in patients who were adhering to HAART medication was not signi ficantly different from those who were not adhering to medication (p = 0.75 and χ 2 = 6.902). The use or lack of use of herbal medicine is not a determinant for adherence. The most profound reason for herb use was to improve treatment. However, herb/drug interaction studie s are imperative to ascertain if interactions occurring are beneficial or harmful. The pharmacist must counsel and re -counsel patients on HAART, not to use herbal products with their antiretroviral medications to avoid drug -herb interactions which could be potentially life threatening.