The effects of nimodipine, a calcium antagonist with preferential cerebrovascular activity, on the global and regional cerebral blood flow (CBF and rCBF), the intracranial pressure (ICP), and the cerebral perfusion pressure (CPP), were investigated in an acute study. The rCBF of 54 patients was measured by the Xe133 inhalation method under identical conditions before and 60 min after oral administration of nimodipine. 12 patients with focal cerebral circulation disturbances of arteriosclerotic origin, who had suffered a cerebral accident (TIA, PRIND, minor stroke) no more than 3 weeks previously, were given a placebo (test-retest controls) and 25 patients of the same diagnosis and age group were given 40-80 mg nimodipine orally. 11 patients with acute subarachnoid hemorrhage (SAH) from ruptured anterior communicating artery aneurysms and clinical and angiographic signs of vasospasm (Hunt- and Hess grade 3) were likewise treated with nimodipine by the oral route. 6 patients with cerebral vasospasm received nimodipine in i.v. doses of 0.5-2 mg/h. The cerebral blood flow, assessed on the basis of the initial slope index (ISI), before and after the medication, was compared by statistical methods. 12 patients with head injury were given nimodipine intravenously in a dose of 0.5-2 mg with continuous monitoring of the ICP and the blood pressure. The pressure values were evaluated continuously by computer, with calculation of the perfusion pressure, and tested for statistical significance. Oral nimodipine therapy resulted in a significant (14%) increased of the CBF (taking account of the arterial pCO2), the improvement of blood flow being even more pronounced in the hypoperfused regions.(ABSTRACT TRUNCATED AT 250 WORDS)