• Researchers have found level of intellectual functioning to effect rate of comorbid symptoms. • Presence of comorbid symptoms were examined in children with ASD and children with ASD and ID. • No significant differences in presence of comorbid symptoms were found between the groups. • Despite these findings, level of intellectual functioning should be taken into account when designing treatment programs. Research is limited in examining the presence of comorbid symptoms in children and adolescents with autism spectrum disorder (ASD) and co-occurring intellectual disability (ID). The current study aimed to expand knowledge in this area by evaluating the presence of comorbid symptoms in children and adolescents with ASD, compared to those with ASD and ID. Comorbid symptoms examined using the Autism Spectrum Disorders-Comorbidity for Children ( ASD-C-C ) included tantrum behavior, repetitive behavior, worry/depression, avoidant behavior, under-eating, conduct problems, and over-eating. Two hundred and nineteen children and adolescents ranging from 3 to 16 years of age participated in the study. Significant differences were not found between the groups on any of the comorbid symptoms measured. The implications of these findings on treatment are discussed.