Max Karukivi,1,2 Kirsi-Maria Haapasalo-Pesu3 1Unit of Adolescent Psychiatry, Satakunta Hospital District, Pori, Finland; 2Department of Psychiatry, Turku University Hospital, University of Turku, Turku, Finland; 3Psychiatric Care Division, Satakunta Hospital District, Harjavalta, Finland Background: Adolescence is a developmentally sensitive stage, during which a medical illness may have an effect on individual development, and vice versa. Chronic medical illnesses in adolescents have been associated with psychiatric symptoms. The aim of the present register-based pilot study was to assess whether, and to what extent, different medical diagnoses predict subsequent use of mental health services among adolescents. Methods: The study material comprised data on visits to a pediatric clinic by 12- to 16-year-old adolescent patients over a period of 5 years. Altogether, 10,154 visits by 1,781 patients were identified. The associations of the medical diagnoses with a subsequent visit to the adolescent psychiatry clinic were analyzed using logistic regression. Results: During the follow-up period, 299 patients (16.8%) visited or contacted the adolescent psychiatry clinic at least once. Of various diagnoses, the highest odds ratios (ORs) were observed for diabetes mellitus (OR=4.07, p<0.001) and neoplasms (OR=3.29, p=0.047). An association was found between adolescent psychiatry clinic visits and female gender. Conclusion: Medical symptoms and illnesses that require a referral to a pediatrician are a marked risk factor for later use of mental health services. The results call for screening for psychological distress among patients with somatic illnesses and prompt referrals to mental health services if required. Keywords: adolescents, adolescent psychiatry, medical illness, mental health care, pediatrics