Introduction In many sub-Saharan African countries, most new cases of Human Immunodeficiency Virus (HIV) infection occur in HIV sero-discordant couples. This study assessed the sexual behaviour of HIV positive men accessing comprehensive services at Nigerian Institute of Medical Research Lagos.

Methods A cross sectional study was carried out among men accessing ARV at a PEPFAR Clinic. Ethical approval was obtained. Respondents were recruited consecutively on clinic days among the attendees until calculated sample size of 384 was attained. Data was analysed using IBM SPSS version 20. Association was explored using p<0.05.

Results The mean age was 43.06 years. 74.8% were married at diagnosis, 58.1% tested with their partner, 78.5% knows the HIV status of their partners and 79.2% had been on ARV for more than a year. With respect to sexual behaviour, 38.9% and 34.3% engage in transactional and intergenerational sex respectively. 21.1% and 8.3% were into concurrent multiple sexual partnerships in the twelve months and three months preceding the survey. 7.2% had sex with casual partners or sex workers, 45.4% did not use condom consistently, among these men, 18.1% did not use condom at last sex and the last sexual partner for 7.9% was a sex worker/casual friend. Unmarried respondents were more likely to have concurrent multiple partners (p<0.001) and use condoms inconsistently (p<0.001). Married men were more likely to know the HIV status of their partners (p<0.001) and to have disclosed to others (p=0.020). Respondents who engage in intergenerational sex were more likely to have transactional sex (p<0.001) and not used condom at last sex (p=0.010). Transactional sex was commoner among men who practice concurrency (p<0.001) and did not use condom at last sex (p=0.005).

Conclusion The sexual behaviour of this study population closely aligns with that of men in the general population with respect to risk taking. Targeting HIV positive men for sexual behaviour change will therefore contribute towards eliminating new HIV infections.