The authors report on six cases of cerebral tumours: three astrocytomas (two temporal and one frontal), two meningiomas (one parietal and one frontal), and a metastasis with a temporal location causing sensory-motor epileptic seizures ipsilateral to the lesion. The discussion includes comments on the pathogenesis of these manifestations viewed in the light of experimental and electrophysiological data, and on the hypotheses of the "mirror focus", irritation of the supplementary motor and secondary somato-sensory areas, compression of the opposite hemisphere, and possible absence of decussation of the sensory-motor pathways. The false localization suggested by this type of paroxysmal senzures and their rare clinical occurrence is emphasized.