Studied was an effect of pentoxyfilline on systemic and cerebral haemodynamics in 33 patients with discirculatory encephalopathy in the presence of atherosclerotic lesion of the precerebral arteries, with the aid of dye-dilution methods using Evans blue (T-1824) and ultrasonic dopplerography. Pentoxyfilline was found to be associated with significant reduction of the circulating blood volume at the expense of its globular fraction, diminution of the cardiac and stroke work indices; the drug has only minor effects on the peripheral vascular resistance and linear velocity of bloodflow in the precerebral arteries; it makes for an increased number of cases of eukinetic type of blood circulation and causes regression of subjective neurologic symptomatology. On account of its antihypertensive and cardiodepressive effect the drug is contraindicated in patients with low AP and hypokinetic type of systemic haemodynamics. If intracerebral steal syndrome is detected, the institution of the pentoxyfilline therapy cannot be recommended.