The operating characteristics and base rate effects of tests and indexes in the Halstead Russell Neuropsychological Evaluation System—Revised (HRNES-R) were obtained to determine its accuracy in assessing brain damage. Since operating characteristics and base rate problems are not well understood they were discussed in some detail. The operating characteristics of Sensitivity, Specificity, Positive Predictive Power, Negative Predictive Power and Overall Predictive Power along with base rate effects were obtained for 2 HRNES-R indexes, 10 index tests and 3 other Halstead Reitan Battery (HRB) tests. The indexes were found to be as accurate as the most accurate indexes from other HRB studies. The accuracy of the various tests were high but varied according to their function and design.