We assessed the reliability and validity of the Turkish version of the autism spectrum quotient (AQ)-adolescent. Three assessment groups of adolescents, aged 11-18, were: 80 with Asperger syndrome/high-functioning autism (AS/HFA), 71 with other psychiatric disorders (PDs; 35 major depression, 18 obsessive-compulsive disorder, 18 social phobia), and 249 healthy controls. The scores of the AS/HFA group were significantly higher than the healthy control and PD groups. Cronbach a value was 0.829. Ordinal alpha value was 0.90. We showed the AQ-adolescent four-factor structure in the factor analysis. In the test-retest of AQ-adolescent and subscale scores, "very strong" significant correlation values were detected. A cut-off score of 24 best distinguished the autism group from healthy controls with 0.975 sensitivity and 0.991 specificity.