Background: Sex as self-injury has become a concept in Swedish society; however it is a largely unexplored area of research, not yet conceptualized and far from accepted in the research field. The use of sex as a way of affect regulation is known in the literature and has, in interviews with young women who sell sex, been compared to direct selfinjury, such as cutting or burning the skin. The aim of this study was to investigate the self-reported frequency of sex as self-injury and the association to sociodemographic factors, sexual orientation, voluntary sexual experiences, sexual risk-taking behaviors, sexual, physical and mental abuse, trauma symptoms, healthcare for psychiatric disorders and non-suicidal self-injury. Methods: A representative national sample of 5750 students in the 3rd year of Swedish high school, with a mean age of 18 years was included in the study. The study was questionnaire-based and the response rate was 59.7%. Mostly descriptive statistics were used and a final logistic regression model was made. Results: Sex as self-injury was reported by 100 (3.2%) of the girls and 20 (. 8%) of the boys. Few correlations to sociodemographic factors were noted, but the group was burdened with more experiences of sexual, physical and emotional abuse. Non-heterosexual orientation, trauma symptoms, non-suicidal self-injury and healthcare for suicide attempts, depression and eating disorders were common. Conclusions: Sex used as self-injury seems to be highly associated with earlier traumas such as sexual abuse and poor mental health. It is a behavior that needs to be conceptualized in order to provide proper help and support to a highly vulnerable group of adolescents.