The aims of the current study were to provide the first Australian prevalence estimates of sexual harassment in adolescents, explore gender differences in form and frequency of harassment, and investigate demographic and weight status correlates. A total of 4098 adolescents (47.3% boys), aged 11 to 19 years from government and non-government secondary schools completed demographic questions, self-reported weight and height, and a modified Association of American University Women Sexual Harassment Survey. Overall, 42.5% of boys and 40.0% of girls reported some forms of sexual harassment in the previous school term. A significant gender difference was found in overall frequency of sexual harassment but not in prevalence. Six of the nine forms of sexual harassment were more likely and more frequently to have been experienced by boys compared to girls. In conclusion, sexual harassment is a pervasive problem in Australian high schools and needs to be acknowledged and dealt with specifically.