Six cases of partial epilepsy operated on for lesions at the temporo-parieto-occipital junction are presented. Three cases had signs of enlargement of one lateral ventricle at the temporo-parieto-occipital carrefour, three had a lateral homonymous hemianopsia and all showed lateralizing interictal EEG abnormalities. The manifold features of the seizures could not be related to the involvement of one or more definite cortical areas. Since clinical, radiological, scalp EEG investigations provided no sufficient data to map the epileptogenic lesion to be excised, stereo-EEG studies with chronic depth electrodes were performed. Besides permitting the exact delimitation of the epileptogenic lesion, depth EEG gave the clue for interpreting physiopathological mechanisms underlying the electroclinical seizures in each case.