Clinical heterogeneity is a well-established characteristic of autism spectrum disorder (ASD). While the comorbidity of ASD and ADHD is well known in clinical practice, relatively little research has examined the neuropsychological profile of children with ASD + ADHD. Our study showed significant differences in the neuropsychological characteristics of children with ASD + ADHD compared to those with ASD only. Children with ASD + ADHD showed higher symptoms of anxiety, worse working memory, and less empathy, as measured by the "Reading the Mind in the Eyes." This suggests that having ADHD brings further challenges to individuals with ASD and may negatively impact their management and outcome. Our findings may have implications for clinical assessment as well as for intervention.