Résumé : Introduction. Men who have sex with men (MSM) are a high-risk population for STIs/HIV in the Central African Republic (CAR). Our study aimed to test the effectiveness of the combination of behavioral, biomedical and structural interventions in MSM in the context of a security crisis. Materials and methods. The interventions were conducted from June 2014 to October 2016. Participants (n=215) were enrolled in the National Reference Centre for STIs and Antiretroviral Therapy in Bangui, the capital city of CAR. The intervention group (n=40) was randomly selected. The remaining subjects (n= 175) was the control group. Both groups participated in a series of STI/HIV upgrading training sessions at the beginning of the study. Then, intervention group received 1) biomedical interventions (antiretroviral treatment as prevention, STI diagnosis and treatment, and HIV counseling), 2) psychosocio-educational interventions (interactive training, educative talks, social assistance and text messages) and 3) Structural interventions: (condoms available and free of charge). Results. In the intervention group, the median of casual sexual partners in the previous three months was significantly reduced (p < 0.001) ; the percentage of MSM having 100% of protected intercourse increased significantly (p<0.001). Only one MSM out of 40 was infected with HIV versus nine out of 76 in the control group. No negative subjects in the intervention group became positive for hepatitis B. There was no significant increase in the number of new cases of syphilis infection (p<0,001). Conclusion. The combination of interventions has an alleviating impact on risk behaviors and probably reduces the incidence of STI/HIV among MSM, even in times of humanitarian crisis. In view of the small sample size, it would be necessary to carry out a more in-depth study with a larger sample of MSM, in order to confirm these results.