Objective. The primary objective of this study was to compare the adult-onset and adolescent obsessive-compulsive disorder (OCD) patients in terms of the subthreshold autistic traits. Methods. 29 adolescent, and 45 adult-onset OCD patients were assessed by Autism-spectrum Quotient (AQ). Results. The ratio of males to females, the frequency of ritualistic compulsions, and the mean number of lifetime compulsions were significantly higher in adolescents with OCD compared to adult-onset patients. Adult-onset OCD patients had significantly higher scores on total, social skills, attention shifting, and imagination subscales of AQ than adolescent OCD patients. The mean number of compulsions, attention shifting scores of AQ, and female gender significantly predicted the distinction between adolescent and adult-onset OCD patients. In adult-onset patients, there were significant correlations between the mean number of lifetime obsessions and total, social skills, attention switching, communication, and imagination subscale scores of AQ. Conclusions. We suggest that subthreshold autistic traits may play a significant role in the occurence of obsessive-complusive symptoms (OCS) in adult-onset OCD. Autistic traits seemed to be higher and had an closer relationship with the frequency of lifetime obsessions in AO-OCD patients than in adolescent patients.C1 [Memis, Cagdas Oyku; Dogan, Bilge; Baygin, Cansu; Sevincok, Levent] Adnan Menderes Univ, Dept Psychiat, Aydin, Turkey.[Sevincok, Doga; Ozbek, Mutlu] Adnan Menderes Univ, Dept Child & Adolescent Psychiat, Aydin, Turkey.[Kutlu, Ayse] Child Dis & Pediat Surg Training & Res Hosp, Dept Child & Adolescent Psychiat, Izmir, Turkey.[Cakaloz, Burcu] Pamukkale Univ, Dept Child & Adolescent Psychiat, Denizli, Turkey