The purpose of this study was to investigate sex differences in behavioral and emotional problems in high-functioning girls and boys with autism spectrum disorder. The results obtained by adolescents with autism spectrum disorder were compared with those of typically developing girls and boys. Correlations between parents’ and adolescents’ ratings were also analyzed. Participants were 35 girls and 35 boys with autism spectrum disorder, aged 11–18 years, matched for chronological age and full-scale IQ. The control group consisted of 24 typically developing girls and 24 boys of the same age and IQ. The parents of adolescent participants were also included in the study. The measures used were the Child Behavior Checklist (4–18) completed by parents and Youth Self-Report (11–18) completed by adolescents. The adolescents with autism spectrum disorder presented higher levels of behavioral and emotional problems than the control group, according to both the parents’ reports and the adolescents’ self-reports. No sex differences were found in that respect. More differences between the assessments of adolescents and their parents occurred in the control group, and the effect size was larger.