The aim of this study was to estimate the prevalence and factors associated with unprotected receptive anal intercourse (URAI), stratified by age (18-24 or 25 + years old), in a sample of 4,129 MSM recruited by respondent driven sampling in 12 Brazilian cities in 2016. The prevalence of URAI was higher among younger MSM (41.9% vs 29.7%) (p < 0.01). Multivariate analysis indicated that perception of risk, sexual identity, self-rated health status, and having commercial sex were associated with URAI among younger MSM. History of sexual violence, sex with younger partners, having 6 + partners and unprotected sexual debut were associated with URAI among older MSM. Marital status, having stable partner, and reporting sex with men only were associated with URAI in both groups. Despite access to condoms and lubricants, preventive efforts may not be reaching MSM effectively. Age specific intervention approaches, including stigma, discrimination, and perception of risk must be considered.