The protective properties of PY 108-068 against ischemic disturbances in the brain were investigated in vitro and in vivo. The calcium antagonistic effects were demonstrated on isolated, calcium-loaded arterial rings of feline cerebral arteries. Determination of brain tissue oxygenation with pO2 microelectrodes showed that PY 108-068 improved oxygen supply in the cortex of cats subjected to epicerebral arterial occlusion. In a model of cerebral vasospasm induced by autologous blood superfusion, PY 108-068 reversed the spastic state of cortical microvessels. In a chronic stroke model (microsphere embolization in rats) PY 108-068 led to a significant reduction in mortality and in the severity of neurological symptoms, whereby the peroral efficacy of the drug could be demonstrated. The efficacy of PY 108-068 in a variety of ischemic insults makes this drug a promising aid in the treatment of cerebrovascular accidents.