Abstract: A genetic epidemiologic case-control study including 214 prdigrees( 109 cases and 105 controls)was carried out to estimate the heritability(h²)and the segregation ratio of arteriosclerotic cerebral infarcation by using the methods of Falconer and Li-Mantelfiart respeckively in Yi Xing city, March 1997. The results showed that the nuclear family members were well comparatively. The segregation ratio was 0. 0529,which was significantly less than 0.25. The theoretical incidence rate thefirst rank blood relatives in cases was 6. 678%，which was no significantly difference from actual rate (8. 611%).and P value was larger than 0.05, It means that the geneticmodel belonged to polygenetics.The heritability of the first rank blood relatives wasequal 53070(in male and female, they were respectively 39.4% and 57%).It suggested that the hereditary fact or was important in the occurance of artariosclerotic carahral infarction.