Many children with autistic disorder, or autism, are described as having low intelligence quotients. These descriptions are partially based on use of various editions of the "Wechsler Intelligence Scale for Children" (WISC), the most widely used intelligence test for children with autism. An important question is whether task demands of the Wechsler scales are sensitive to unique characteristics of children with autism that might affect test performance. Another question relates to how changes in the newest edition of the WISC have affected its sensitivity for the population of individuals with autism. The administration guidelines and task demands of the third (WISC-III) and fourth (WISC-IV) editions were examined to determine appropriateness when measuring intelligence of children with autism. Implications related to use of these instruments with children with autism are discussed. (Contains 3 tables.)