Background: HIV infection has been shown to be high among military personnel in sub-Saharan Africa. Furthermore, research has shown inconsistent condom use is common in African military populations. In an effort to determine the prevalence of HIV, quantify condom use, and investigate correlates of condom use, a cross-sectional seroprevalence study was implemented in the Armed Forces of the Democratic Republic of the Congo (FARDC). Recent condom use behaviors and correlates of low condom use were also assessed. Methods: From October 2013-April 2014, 2,701 sexually-active FARDC soldiers, aged 19-83, participated in the study. Participants from 30 military sites were administered a survey via personal interview by a trained FARDC counselor. The survey collected information on demographics, military characteristics, and HIV risk behaviors such as condom use. Results: The seroprevalence of HIV was 3.5%. After adjustment, primary risk factors associated with HIV infection included: not being married, multiple regular partners in the past 12 months, screening positive for PTSD, and testing positive for active syphilis infection (p<0.05). After stratification by region, participants in the Eastern region were found to have the highest HIV prevalence at 5.1%. HIV testing frequency was also found to be associated with HIV infection, with participants who reported ≤1 test since joining the military being more than three times more likely to test positive. Furthermore, 85% of male participants reported rarely/never using condoms. Lower condom use was associated with condom accessibility, reduced sexual pleasure, trust issues with condoms, negative attitudes towards condoms, and lower knowledge of HIV prevention and transmission. Conclusions: The HIV prevalence in the FARDC is about three times higher than the general population, indicating a concentrated epidemic. HIV prevention interventions aimed at increasing condom use in the FARDC should address issues of accessibility and trust. The FARDC should consider providing scented condoms and reinforce the importance of correct and consistent condom use. Results suggest that a mental health program focused on PTSD and a syphilis awareness and treatment campaign would be beneficial to the FARDC. Routine HIV testing should also be implemented in the FARDC.