For the first time, the Prevagay study was conducted in Montpellier, with the primary objective of estimating HIV prevalence among men who have sex with men (MSM) frequenting gay social venues in that city and describing the characteristics of MSM infected with HIV. The study was conducted using a cross-sectional, anonymous, and random approach among MSM frequenting bars, saunas, and backrooms in Montpellier, as well as in Paris, Lille, Nice, and Lyon. Behavioral data were collected via questionnaire, along with blood samples collected on 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 Lyon, 266 MSM who frequented the 13 social venues investigated agreed to participate. Half of them were over 42 years old. More than 86% identified as homosexual. Nearly 45% had had more than 10 sexual partners in the past 12 months. As in other cities, condom non-use was significant and more pronounced among HIV-positive MSM. HIV prevalence was estimated at 16.9% [95% CI: 11.2–24.7]. This prevalence, significantly higher than in Lille, was not different from those observed in other cities. Among HIV-positive MSM, 95% had been diagnosed, and 99% of them were on antiretroviral therapy. These results support strengthening the promotion of various protection methods and diversified prevention strategies during outreach activities in gay social venues.