Four hundred and fifty six third year undergraduate students from the University of Nairobi, Kenyatta University and Egerton University were studied to find out the influence of self-concealed psycho-social factors as predictors on the effectiveness of sexual self-disclosure during voluntary counselling and testing among university students in Kenya. Results revealed there is a significant relationship between self-concealed psycho-social factors and sexual self-disclosure. Students’ marital status, relational mobility and cues that relate to privacy were found to be the best predictors of sexual self-disclosure by determining details of how much sexual information they disclosed during voluntary counselling and testing. Implications of these findings and recommendations for further research are discussed.