ABSTRACT Background Vulvo-vaginal candidiasis is the most frequent initial clinical gynaecological manifestation of HIV infection and its presence can enhance the propagation of HIV infection in sero-discordant couples, in addition to increasing morbidity in HIV positive women. Aim To determine the prevalence of vulvo-vaginal candidiasis in HIV seropositive women in Lagos—Nigeria. Method A cross sectional prospective study of 500 participants aged 15-50 years was carried out at two study centres at LUTH and NIMR between MarchSeptember 2005. Data were collected from 250 HIV positive participants and 250 HIV negative participants using pre-tested questionnaire and clinical and laboratory assessment for the presence of vulvo-vaginal candidiasis. Results The prevalence of vulvo-vaginal candidiasis was higher in HIV positive participants when compared with HIV negative participants. (P<.05 for all comparisms). Sixty-two(24.8%) of HIV positive participants compared with 37(14.8%) in the HIV negative group had vulvo-vaginal candidiasis. (OR=1.90,CI=1.18—3.07,P=0.005) Cultured candida isolates following sugar fermentation were more likely to be of the non-albicans sub-species in the HIV positive group compared with candida isolates from HIV negative participants. (OR= 0.03, CI= 0.01—0.10, P= 0.0001). In the HIV positive group, of the sixty-two participants with vulvo vaginal candidiasis, those with CD4 cell count <200/mm3 were at a higher risk of having vulvo-vaginal candidiasis when compared with participants with CD4 cell count >200/mm3. (OR= 15.93, CI=7.31—34.81, P=0.001) Conclusion The prevalence of vulvo-vaginal candidiasis was higher among the HIV positive participants, in whom the candida infection were also more likely to be caused by the non-albicans subspecies, and the risk of having vulvovaginal candidiasis higher when the CD4 cell count was <200 cells/mm3