Purpose: To describe sexual health risks in an understudied group, youth in detention, and compare these to sexual health risks among non-detained youth. In addition, variables predicting adverse sexual health outcomes are sought and compared. Methods: In 2009, a self-administered questionnaire on sexuality was conducted amongst youth in Sweden. In 2010, the same Internet-based questionnaire was applied in a study at Swedish detention centres. In this article, sexually active youth aged 15–20 years in the two groups are compared and bivariate logistic regression analyses are conducted in order to find predictors of adverse sexual health outcomes, among detainees and non-detainees respectively. Results: Major differences between the detained and the non-detained concerning a majority of risk-taking variables exist. Conclusions: Although detained youth display several risky sexual behaviors, no specific risk factors are found in a logistic regression analysis. However, this is a vulnerable group. The mere fact that an adolescent is placed at a detention centre should be an imperative for professionals to address the subject of sexual health and safer sex. Furthermore, the results will be used in a forthcoming sex education curriculum tailored especially at detained youth. This is one, but by far not the only way to minimize the health inequalities that are presented in this study.