The application of the nine-subtest prorated version of the Wechsler Adult Intelligence Scale-III (WAIS-III) in estimating Verbal, Performance, and Full-Scale IQ scores was evaluated in a sample of 278 mixed clinical patients from two Department of Veterans Affairs Medical Centers. The composite reliabilities of the three prorated summary scores, which excluded Comprehension and Picture Arrangement, did not differ from reliabilities from the full WAIS-III. All three prorated IQ summary scores demonstrated good alternate forms reliability with the standard WAIS-III summary scores. Verbal Performance discrepancy scores were accurate for 86% of the cases. The results of this study appear to support the regular use of prorated WAIS-III summary scores in estimating full WAIS-III summary scores. The benefit of this system is that by giving all of the subtests required for the index scores, not only are the index scores derived, but a very close estimation of the summary scores are generated.