We prospectively analyzed MR studies of 32 patients with intractable complex partial seizures, who later underwent resection of EEG-proven seizure foci. Twenty-seven patients were imaged at 1.5, 4 at 0.35, and 1 at 0.5 Tesla. Correlation was obtained on all patients with EEG and surgical pathology. Of 19 patients with mesial temporal sclerosis (MTS), 13 exhibited an MR abnormality at the site of pathology as determined by EEG and surgery. Abnormalities included increased (8) or decreased (1) signal intensity, distortion of gray-white interface (1) and temporal lobe atrophy (3). Six patients had no abnormalities at the site of the diseased focus. MR was more sensitive in patients with other structural lesions which included tumor, encephalitis, polymicrogyria, cryptic vascular malformation, and tuberous sclerosis. Prior studies indicate some usefulness of MR in intractable seizure patients, but many report relative insensitivity of MR in defining an abnormality (as low as 11%). Our results demonstrate the usefulness of high-resolution thin-section multiplanar MR using cardiac gating or flow compensation techniques in this patient population.