HIV infection remains a serious issue of community intervention. In this context, many actions are developed and implemented by both public authorities and non-governmental organizations. These are interventions to prevent HIV transmission, overall care, etc. There is a problem of differential propensity according to gender and belonging to social categories access to prevent HIV services. This study aims to identify the explanatory factors for unequal access to HIV prevention services in Benin. Thus, data from the survey on gender-based violence related to HIV collected in 2017 by Plan International Benin were used. The sample size is 929; composed of vulnerable and key populations. Access to prevention services is a composite indicator based on four variables (screening, condom promotion, management of STIs, information, education and communication (IEC) and Communication for Behavioral Change (CBC)). The analysis is done using SPSS.21 software. The bi-varied association was performed using Pearson’s Chi2 and Fisher’s F tests and prediction of explanatory factors by logistic regression. In both 929 populations, 64.5% (599) are key populations and 35.5% (330) are vulnerable. In total, 22.5% (209) population did not have access to prevention services including 66.5% (139) of vulnerable people. Adolescents under 20 years of age (50.8%), females (25.6%), singles (27.2%), farmers (61.1%) and people living in rural areas (43.4%) are more likely not to benefit from HIV prevention services. Five factors predict unequal access to prevent HIV interventions (p < 5%). These are social status, marital status, education level, occupation and department of residence. Indeed, the: 1) vulnerable people (OR = 4.54), 2) divorced/widowed (OR = 1.77), 3) uneducated (OR = 1.61), 4) farmers (OR = 2.18) and 5) people living in the departments of Mono-Couffo (OR = 2.57) have the highest odds ratio of poor access to HIV prevention services. From the above, it is necessary for the establishment of a mechanism to facilitate vulnerable people, especially women, access to HIV prevention services. In addition, there is a need to ensure global coverage of the availability and geographical accessibility of prevention services with particular attention in the department of Mono-Couffo.