SummaryThe greatest concentration of radioactive microspheres, injected into the vertebral artery, was found in pons, medulla and cerebellum. Under barbiturate anaesthesia. local administration of angiotensin, 10 ng/kg, or noradre-naline, 100 ng/kg, increased the amount of microspheres arriving in the intracranial structures and decreased the amount arriving in the neck muscles. Under chloralose anaesthesia, angiotensin 10 ng/kg, decreased the amount of microspheres in intracranial and extracranial tissues. This angiotensin-dose did not provoke hypertension.