Introduction – Young people aged 15–25 are particularly affected by certain sexually transmitted infections (STIs). The aim of this study is to describe trends over time in screening and diagnosis of HIV and three bacterial STIs (chlamydia, gonorrhea, and syphilis) among young people aged 15–25. Methods – This article presents trends in testing rates and diagnosis rates for HIV and three bacterial sexually transmitted infections (STIs) (chlamydia, gonorrhea, and syphilis) among young people in France from 2014 to 2023, and compares them to rates observed among adults. “Young people” include those aged 15 to 24 versus “adults” aged 25 to 49 for HIV, and those aged 15–25 versus 26–49 for bacterial STIs. The data are drawn from the National Health Data System and mandatory HIV reporting. Results – The rates of people tested for the four STIs have increased by between 44% and 593% among young people and by between 36% and 225% among adults since 2014. The increase (+41%) in the number of new HIV diagnoses among young people between 2014 and 2023 contrasts with the decrease (-15%) observed among adults. This trend reflects an increase in HIV diagnoses among young people born in sub-Saharan Africa and a stabilization among young men born in France who have sex with men. An increase in gonorrhea diagnoses among young people, as well as an increase in chlamydia diagnoses among young men, was also observed. Conclusion – The increase in STI diagnoses among young people underscores the importance of targeted prevention strategies, such as access to free condoms and the implementation of walk-in testing, to support efforts toward the elimination of these STIs.