This article presents data from mandatory HIV reporting among young people (ages 15–24) in France: on the one hand, among young adults (ages 18–24) in 2013 and since 2003, and on the other hand, among adolescents aged 15–17 over the cumulative period of 2003–2013, due to limited sample sizes. In 2013, 726 young people aged 15 to 24 learned they were HIV-positive, representing 11.7% of all new diagnoses and a rate, relative to the population of the same age, of 92 per million inhabitants. Among the 686 young adults (aged 18–24) diagnosed in 2013, two-thirds (68%) were men, the majority of whom were infected through sex between men (75% of them). Since 2003, the number of new HIV diagnoses in this group has risen sharply (+157%). Nearly all (98%) of the young women were infected through heterosexual intercourse; 71% of them were born abroad. The proportion of young adults infected through injection drug use was low (0.4%). Approximately 14% of diagnoses in this age group were late-stage (<200 CD4/mm³ or AIDS stage). Among the 524 adolescents aged 15–17 who learned of their HIV-positive status between 2003 and 2013, nearly two-thirds were women (65%), primarily born abroad and infected through heterosexual intercourse. The primary mode of transmission among male adolescents was sex between men (for 49% of them). Nearly 6% of HIV diagnoses among adolescents were linked to mother-to-child transmission, which was diagnosed late. HIV prevention efforts targeting adolescents and young adults must continue, particularly among young men who have sex with men.