The substance use disorder (SUD) is one of the most common disorders in adolescence. The lifetime prevalence is 3% to 32%. Alcohol and tobacco are the most used licit substance and cannabis is the most commonly used illicit substance. Studies indicate that approximately 75% of patients with SUD have psychiatric comorbidities such as conduct disorder, attention-deficit/hyperactivity disorder (ADHD) and affective d<a name="_GoBack"></a>isorder. Adolescents with SUD and comorbid mental disorder have high risk for continuing problems in adulthood. The costs of treating SUD and a psychiatric comorbidity is twice as high when treated separately.

To find the prevalence of psychiatric comorbidities in adolescentes with SUD.

The diagnostic instrument Kiddie-Schedule for Affective Disorders and Schizophrenia for School aged Children 6-18years (K-SADS-PL) was used to identify SUD and all psychiatry disorders in adolescents admitted to a clinic for SUD treatment.

In a sample of 30 adolescents with SUD, 8 adolescents (26,6%) has ADHD comorbid and 14 (46,6%) has conduct cisorder comorbid. Four (13,3%) patients has affective disorder comorbid.

Early diagnosis of a psychiatry comorbidity can improve the treatment in adolescence and prevent further complications such as legal and medical problems, suicide, learning difficulties, school dropout, unemployment and interpersonal relationship problems.