For the first time, the Prevagay study was conducted in five different cities: Nice, Montpellier, Lyon, Lille, and Paris. The main objective of this study was to estimate the prevalence of HIV among men who have sex with men (MSM) frequenting gay social venues in these cities (bars, saunas, and backrooms) and to describe the characteristics of MSM infected with HIV. The study was conducted cross-sectionally, anonymously, and randomly between September and December 2015. Behavioral data were collected via questionnaire, along with blood samples collected using filter paper. HIV antibody testing was performed by the National HIV Reference Center. Among the positive samples, viral load testing and antiretroviral treatment status were assessed. In total, 2,646 MSM who frequented the 61 venues investigated agreed to participate. Half of them were over 41 years old. More than 83% identified as homosexual. Nearly 45% had had more than 10 sexual partners in the past 12 months. Condom non-use was significant and more pronounced among HIV-positive MSM. The prevalence of HIV was estimated at 14.3% [95% CI: 12.0–16.9]. It varied by city and age. Prevalence was particularly high in Montpellier (16.9% [95% CI: 11.2–24.7]), Nice (17.1% [95% CI: 11.8–24.1]), and Paris (16.1% [95% CI: 12.5–20.4]), whereas it was significantly lower in Lille (7.9% [95% CI: 5.1–11.1]). In Lyon, the prevalence was 11.4% [95% CI: 6.9–18.3]. Among those under 25, it was 4.4%. Among HIV-positive MSM, 91.9% had been diagnosed, of whom 93.5% were on antiretroviral therapy. No significant differences were observed between cities for these two indicators. These results support the continued promotion of various protection methods as part of a diversified prevention strategy during outreach activities in gay social venues.