Positron scintigrams were obtained in normal subjects and in patients with intracranial tumors and cerebral vascular disease, using a multicrystal positron camera. The radiopharmaceuticals were 68Ga complexed with ATP (68Ga-ATP), 13N-ammonia (13NH3) and 15O2. Six clinical cases were described to illustrate the different cerebral distributions of i.v. administered 68Ga-ATP, 13NH3 and inhaled 15O2. The possible value of these agents in the study of cerebral metabolism and in differential diagnosis of intracranial disease was discussed.