SummaryGamma-encephalography is a new exploration method, introduced by Th. Planiol and based upon the study of the gamma-rays emitted outside the cranium by a radioisotope injected into the circulation.The originality of this method consists in the fact that tracer substances gather in the lesions themselves, especially in space-occupying lesions that become radioactive foci, easy to detect at the level of the scalp.This inoffensive and ambulatory method enables us not only to confirm the existence of a space-occupying intracranial lesion but also to ascertain its nature in most of the cases. Besides it supplies valuable topographic information and it gives a possibility of finding out the postoperative tumoral relapses.The description of three personal cases illustrates the possibilities of this promising method.