Introduction – The emergence of biomedical HIV prevention tools has revolutionized sexual health policies, offering alternatives to condoms. However, their adoption remains limited, particularly among young men who have sex with men (MSM). This study aims to analyze their living conditions, attitudes toward health, and prevention practices within a context shaped by the construction of sexual identity, risk management, and restrictive social norms. Method – Data are drawn from the Sexuality Survey (Eras), conducted in 2023. The analyses focus on 6,371 MSM aged 18 to 29, divided into three age groups: 18–21, 22–25, and 26–29. Results – The 18–21 age group stands out for having a higher proportion of bisexuals (23% versus 15–19%), a mixed social circle (50% vs. 42–43%), and reduced attendance at gay community venues (41% vs. 51–57%). They experience more homophobic slurs (48% vs. 28–37%) and have poorer mental health (40% report anxiety vs. 26–33%). Their access to prevention services is limited: 43% do not discuss this with their doctor, and 46% have not taken an HIV test in the past year (vs. 28–33%). Although condom use is more frequent (34% vs. 29%), their use of pre-exposure prophylaxis (PrEP) remains low (8% vs. 23%), and 43% are at risk of infection (vs. 32–35%). Conclusion – Young MSM aged 18 to 21 appear particularly vulnerable. These disparities reflect both an age-related effect and complex social, identity-related, and geographical factors, highlighting the need to reaffirm prevention strategies tailored to the specific characteristics of a generation growing up amid evolving sexual health tools and standards.