The relationships between Wechsler Intelligence Scale for Children-Third Edition (WISC-R) with the Cognitive Assessment System (CAS) were examined for a sample of 100 children (70 males and 30 females) ages 5 to 16. The sample was comprised of children who were referred to a specialty clinic for evaluation in Tehran. Participants were administered the WISC- R and the CAS. Results indicated that all subtests of CAS/WISC-R correlations were significant. Arithmetic subtest of WISC had high correlation with the four separate CAS scales and full scale, but picture completion subtest of WISC-R had low correlation with the four separate CAS scales and full scale. These results showed that the CAS/WISC-R correlations with achievement were significant.