Cathepsin D (CatD) is a good candidate susceptibility marker for Alzheimer's disease (AD), since it was found to be involved in the processing of the amyloid precursor protein and the formation of the hyperphosphorylated tau. And recently, a CatD genetic polymorphism was found to be associated with the risk of Alzheimer's disease (AD) in a German population. However, the CatD T-AD association has not been replicated in a series of the successive independent studies in other races. Therefore, we determined CatD genotypes to examine the possible association of the CatD polymorphism with AD in Koreans. We failed to find significant association between the CatD T allele and AD. In addition, the CatD T--AD association was not significant regardless of the age at onset or the occurrence of the apolipoprotein epsilon4 allele. However, we cannot exclude the possible contribution of the CatD in the development of AD, since the power of the present study was not high enough because of low allelic frequency of the CatD T in Koreans and small sample size. In conclusion, the association between the CatD genetic polymorphism and AD was not found in Koreans, although it waits for further replication in an extended sample.