For the past four decades, HIV/AIDS epidemic has grown and become generalized in most of sub-Saharan Africa countries, cohabiting couples contribute significant fraction of transmission. However, majority of them do not know their HIV sero-status or test by proxy. We promoted uptake of HIV couple counselling and testing services in northern Tanzania to understand prevelance and determinants of HIV infection among couples presenting for services. We found that prevalence of HIV discordance was high in Moshi and Arusha towns; and positively associated with age and age difference between partners. In such unions, the risk of HIV infection to the uninfected partner increases. We recommend promotion of couples counselling and testing services by using different media to as strategy to maximize access of ART for prevention purposes among discordant couples.