Deoxyribonuclease I (DNase I) polymorphism n exon 8 (A2317G) designated as DNASEI is considered to be one of the susceptibility genes for gastric and colorectal carcinoma, and myocardial infarction. Moreover, the presence of a variable number of tandem repeat (VNTR) polymorphism, designated as HumDN1, in intron 4. was found. In this study, the simultaneous genotyping of DNASEI and HumDN1 polymorphisms within the DNase I gene was performed in Ovambo, Turk, Mongolian, Korean and Japanese populations. Genotype distributions of DNASEI and HumDNI Ioci differed among these populations. While there was a general uniformity for the two polymorphisms in the three Asian populatlons, a significant difference in genotype distribution were found between the Ovambo and Turk populations. The DNASE1*1 and HumDN1*3 alleles were found to be the most predominant in the Ovambos, with the Turks showing the highest allele frequency for DNASE1*2, HumDN1*4 and HumDN1*5. From this study, there was the existence of a certain genetic heterogeneity in the distribution of these two DNase l polymorphisms. Furthermore, linkage disequilibrium between these two polymorphisms was revealed in all of the populations except the Ovambos. The combination of the two polymorphisms within a DNase I gene may be potentially useful for clinical purposes and in population genetic studies.