In the present study the structure of obsessive-compulsive phenomena in non-clinical adolescents was investigated by 'The Padua Inventory' (PI). The PI is a self-report measure of obsessive and compulsive symptoms which is used in clinical and research settings. The use of PI in adolescents has been limited by the lack of normative data. Consequently, adolescent validation has both theoretical and practical implications. PI was administered to 566 normal Italian high school subjects, ranging in age from 15 to 18 years. The mean total score of PI and the mean score of 'mental activities', 'becoming contaminated' and 'urges and worries' sub-scales points to significant differences between males and females. Females reported more obsessions and cleaning rituals than males. Males show more urges and fears than females. Moreover, our data underline that younger subjects get higher mean scores than older subjects in all scales.