Age- and IQ-balanced 27 children with high-functioning (IQ greater than or equal to 70) pervasive developmental disorder not otherwise specified (HPDDNOS) and 27 children with attention-deficit/hyperactivity disorder (ADHD) were compared on the Japanese version of Wechsler Intelligence Scale for Children Third Edition (WISC-III) and the Childhood Autism Rating Scale-Tokyo Version (CARS-TV). Compared with the ADHD children, the HPDDNOS children scored significantly lower on verbal comprehension, vocabulary, and comprehension, but significantly higher on block design. After controlling for the total CARS-TV score, the HPDDNOS children were significantly more abnormal on "relationships with people," "nonverbal communication," and "general impressions," but less abnormal on "near receptor responsiveness" and "activity level." These differences in cognitive and autistic symptom profiles may help professionals to distinguish clinically between both conditions.