Abstract： To explore the relationship between interleukin-lα(IL-1)C/T polymorphism and Alzheimer's dissease(AD) or vascular dementia(VD)in Han Chinese. Methods The polymorphism of IL-lα and apolipoprotein E(APOE) genotype were examined in patients with AD(n=125),VD(n=70),and nondemented controls(n=93)in the northeastern Chinese by means of polymerase chain reaction(PCR)and restriction fragment length polymorphism(RFLP). Results No significant difference was found in the IL-lα T allele frequency among the three groups. The prdominant polymorphic allele(about90%)of IL-lα was the C allele.THE APOE4 allele was overrepresented in the AD group.The presence of the APOE4 allele did not influence the IL-lα genotype or allele distribution.The prevalence of the IL-lα T allele,particular in the homozygous form(TT),was lower than in the whites,which maybe attributed to the lαck of association between IL-lα C/T polymorphism and AD among the northeastern Chinese. Conclusion The presence of the heterozygous IL-lα T allele cannot be used for distinguishing AD or VD from controis.