Thirty-eight patients who had undergone either a right (RTL, n = 19) or left (RTL, n = 19) en bloc unilateral temporal lobectomy were scanned using magnetic resonance imaging, and the extent of removal of the superior lateral (SL), inferolateral (IL), basal, parahippocampal, and hippocampal regions was rated using semiautomated analysis. Brain regional ratings were correlated against pre- versus postoperative changes in memory functioning. The results showed overall significant postoperative decline in verbal memory only in the LTL group. Despite this, in the RTL group basal and hippocampal region removal was correlated with visuospatial memory outcome. In the LTL group, IL and basal region removal was correlated with Performance Intelligence outcome. In each case, more resection was associated with worse functioning and vice versa. It was concluded that variability in neuropsychological outcome can be explained in part by variations in the extent of tissue removal within the en bloc operation.