Chlamydia trachomatis infection is the most common bacterial sexually transmitted infection among young adults. Although it is often asymptomatic, it can lead to serious complications if left undiagnosed and untreated. In the Île-de-France region, surveillance data show a steady increase, particularly among 15- to 25-year-olds. This trend reflects both a real increase in cases and improved screening. Highlighting these regional data allows for better targeting of prevention, screening, and treatment efforts to limit transmission and protect the sexual health of residents in the Île-de-France region.