Although the Weschler Adult Intelligence Scale-Revised (WAIS-R) is not designed to be a neurodiagnostic instrument, it is routinely employed along with neuropsychological tests to assist in clinical decisions regarding the surgical treatment of patients with intractable epilepsy. The Satz-Mogel (SM), a selected-items short form that estimates WAIS-R IQs, is employed to reduce assessment time for the patient and/or to allow for more time for the administration of specific neuropsychological instruments. The accuracy and utility of the SM was evaluated with 84 pre-surgery and 48 post-surgery standard WAIS-R protocols that were rescored according to SM decision rules. As in previous work, SM IQs were very highly correlated with the WAIS-R IQs. However, pre- and post-surgically, the SM was significantly different from the WAIS-R FSIQ (pre: t = -3.22, p = .002; post: t = -4.28,p < .001) and PIQ (pre: t = -5.16, p < .001; post: t = -5.64, p < .001). SM VIQ was not significantly different from WAIS-R VIQ (pre: t = 0.49, p = .628; post: t = 1.94, p = .058). Age corrected scaled scores on a number of subtests also were found to be significantly different when employing the SM. According to Weschler's categories of intellectual functioning, 22.6% of the presurgical patients were misclassified relative to WAIS-R FSIQ (14.3% over-estimated, 8.3% underestimated). Caution should be exercised when interpreting the results of the SM with patients with medically refractory epilepsy.