BACKGROUND Interpersonal violence (IPV) is found to be associated with mental health problems and pain disorders such as headache among children and adolescents. It is well-known that adolescents in need of mental health services have experienced IPV more often than adolescents in the general population. However, there has not been much focus on pain conditions in child and adolescent psychiatric populations. METHODS Data from the current study are based on a 3-year follow-up of the CAP-survey, which is a study of adolescents in the child and adolescent psychiatric unit population of St. Olavs Hospital (Trondheim University Hospital). The baseline study was conducted between 2009 and 2011, with 717 participants between 13 and 18 years. All participants were enrolled, or newly referred to the child and adolescent psychiatric clinic. At follow-up, 570 participants completed questionnaire, and 550 completed a diagnostic interview. The participants were aged 16-21 years (mean age 18.6 years). RESULTS A third of the adolescents reported frequent headaches (weekly or daily). Adolescents with more severe mental problems were more likely to experience frequent headaches. Adolescents exposed to unpleasant sexual acts or bullying, reported more frequent headaches than non-exposed participants. Participants exposed to three or more types of IPV seemed to be at particularly high risk of experiencing frequent headache. CONCLUSIONS Both experiences of interpersonal violence and headache are common in this clinical psychiatric population. Clinicians should assess for headache disorders in addition to psychiatric and trauma assessment and provide need-based treatment to enhance chance of recovery among adolescents in mental health services.