The effect of hemodilution was studied in 106 acute ischaemic stroke patients (55 hemodiluted and 51 control subjects). The investigation did not show statistically significant differences between the two groups regarding the mortality rate and the degree of rehabilitation (modified Rankin Scale) but revealed a significant neurologic score (proposed by the Scandinavian Stroke Study Group) in the hemodiluted group. A correlation between the favourable score modification and the degree of hematocrit modification was also observed.