OBJECTIVE: This study was undertaken to discriminate subtypes of obsessive-compulsive disorder in adolescents. METHOD: Forty individuals with obsessive-compulsive spectrum disorders were ascertained from an epidemiological sample of 861 adolescents. Interviews were conducted by child psychiatrists using semistructured diagnostic interviews, including a clinician-rated Yale-Brown Obsessive Compulsive Scale. Discriminant analysis was performed to compare the scores on the Yale- Brown scale of groups with and without comorbid tics and to compare boys and girls. RESULTS: Adolescents with tics were more prone to aggressive and sexual images and obsessions than were adolescents without tics; these differences could not be wholly attributed to sex differences. CONCLUSIONS: The subtypes among unreferred adolescents are similar to those of adult patients with obsessive-compulsive disorder with and without Gilles de la Tourette syndrome. Subtypes evident in adulthood may be established relatively early in the natural course of obsessive-compulsive disorder.