Background There has been little research investigating sexual health in Italy. The aim of the present study was to present time trends over 8 years in sexual behaviour among adolescents. Methods: This study is part of the Health Behaviour in School-aged Children study (sample: 3983 adolescents aged 15 years; 51.9% girls). Measures included sexual initiation, condom use and age of first sexual intercourse. Results: No variation was observed in the prevalence of sexual initiation and in condom use. The mean age of first sexual intercourse decreased among surveyed adolescents. Conclusions: Considering the tendency of Italian adolescents to begin having intercourse at an earlier age, increased knowledge on sexual behaviours is needed to improve sexual health.