Our aim was to assess the outcome with regard to seizures and neurological function in unselected patients undergoing resective surgery involving the perirolandic area, with or without multiple subpial transections (MSTs). All patients who underwent perirolandic cortical resection or MSTs from 1979 to 2003 at the London Health Sciences Centre were identified. Patients were included if they had seizures originating in the perirolandic area, recorded with subdural electrodes, or if they had scalp recorded seizures and a congruent discrete epileptogenic lesion on MRI in the perirolandic area. Most patients had electrocorticography (ECoG) at the time of surgery. Data collected include pre-operative and post-operative neurological deficits, MRI findings, interictal and ictal scalp EEG, interictal and ictal subdural data, ECoG findings, type and extent of surgery, neuropathologic diagnoses, and seizure outcomes. We studied 52 patients (22 females). The average age at the time of surgery was 33 years, and the average post-operative follow-up was 4.2 years. The most frequent aetiologies were neoplastic in 26 patients (50%), vascular in eight (15%), malformations of cortical development in six (12%), Rasmussen's encephalitis in three (6%) and other aetiologies in nine (17%). Surgery involved the pre-central gyrus in 17 patients, pre- and post-central gyrus in 13, the inferior central region in 11, the post-central gyrus in 7, and the pre-central gyrus and mesial frontal area in 2. At last follow-up 16 patients were in Engel class I (31%), 8 (15%) in class II, 14 (27%) in class III and 14 (27%) in class IV. Residual neurological deficits were present in 26 patients (50%), occurred more frequently in patients > or =25 years old (P < 0.05) and were mild in 14 (54%) patients. In univariate analyses, better seizure outcomes (P < 0.05) occurred in patients whose ECoG showed infrequent post-resectional spikes and no spikes distant to the resection margin, and in resections involving the pre-central and inferior rolandic cortex. In unselected patients with intractable perirolandic epilepsy, many of whom have large, complex epileptogenic lesions, various levels of seizure improvement can be achieved in almost 75% through well-planned surgical resections. New, severe post-operative neurological deficits can occur in 23% of these patients and appear to be more frequent in older patients. Whereas scalp EEG provided limited information to guide surgery, findings on interictal ECoG predicted seizure outcome.