Abstract: HIV counselling and testing (HCT) uptake has been consistently poor in Nigeria. The aim of this study is therefore to identify the barriers to and determinants of HCT uptake among adults in Ayedaade Local Government Area (LGA), Osun State, Nigeria. The study employed a cross-sectional descriptive design. A pre-tested, interviewer administered questionnaire was used to elicit information from 500 respondents of reproductive age group recruited from Ayedaade LGA, Osun State, Nigeria by multi-stage sampling technique. The results were analysed using SPSS version 15.0 and determinants of HCT uptake were evaluated using the Chi-square test of association. The results showed that 16% of the respondents ever had HCT while 84% had never accessed HCT. The most important reasons for not accessing HCT were the perception of being in good health without a need for the test (35.6%), non perception of risk of infection (32.1%) and lack of time (11.4%). The determinants of HCT uptake were respondents’ level of education (p = 0.001), marital status (p = 0.001), partner’s approval of HCT (p = 0.001) and partner’s screening status (p = 0.001). The study concluded that adults in the study area did not access HCT basically because of poor risk perception and lack of time. Factors which determined HCT uptake were both personal and partner related. Health education to make people appreciate their risk of HIV infection and importance of HCT should be intensified.