Introduction: Despite routine testing and policies intended to reduce the incidence of HIV infection among military service members, rates of new human immunodeficiency (HIV) infections have remained relatively stable and high compared to the US civilian population. Materials and Methods: Between 2010 and 2023, standardized Centers for Disease Control and Prevention case report data were collected from 806 HIV-positive male service members - representing approximately 77% of all diagnosed cases - at three Department of the Navy HIV Evaluation and Treatment Units responsible for care coordination and surveillance for U.S. Navy and Marine Corps personnel recently diagnosed with HIV. Pearson’s chi-square tests were used to examine associations between demographic, behavioral, and service-related factors. Results: Most service members had male sexual partners (70%) and reported being single at the time of the interview (64%). More than half reported having sex with anonymous partners (58%) and meeting sexual partners on the internet (54%). Interview facility, marital status, drug use, branch of service, and race were significantly associated with a variety of sexual behaviors (i.e., sex [male of female] of sexual partners, meeting sex partners on the internet, having sex with anonymous partners, having sex with injection drug using partners, having sex while intoxicated or high, and exchanging sex for drugs or money). Conclusions: This analysis reveals patterns of HIV risk factors among males serving in the United States Navy or Marine Corps that can be explored in future studies and highlighted the frequency of sex with anonymous partners and using the internet to seek sexual partners in this population.