Sexual assault among males, compared with females, is understudied, and may also be significantly underreported. Past studies have relied primarily on population-based survey data to estimate the prevalence of sexual assault and associated health outcomes. However, survey-based studies rely primarily on self-reports of victimization and may not accurately estimate the true prevalence of male sexual assault victimization. In order to obtain a detailed assessment of sexual assault among males, criminological databases like the National Incident Based Reporting System (NIBRS) may provide an important and unique source of information. The objective of the current study was to use data from the 2001-2005 NIBRS to construct an epidemiological profile of sexual assault among males. Our results suggest that the incidence of sexual assault was higher among young males (less than 19 years of age), with approximately 90% of all cases being reported among members of this age group. Among males of all ages, forcible fondling and sodomy were the most prevalent forms of sexual assault. Results from additional analyses include age- and race-specific rates of male sexual assault, the prevalence and severity of injury, and time trends detailing incidence by time of the day and location of the incident. Our analyses show that sexual assault is experienced by males of all age groups. However, the rate of sexual assault is higher among younger males. Despite some limitations, results from this study suggest that NIBRS data may provide a important complement to survey data for understanding breadth and consequences of male sexual assault. (Contains 7 tables and 3 figures.)