Pentanucleotide tandem repeat markers are interesting for forensic sciences, because they may present less stutter on the electrophoretic pattern We focused on the anaysis of the DNA sequence for each allele at the pentanucleotide STR locus D10S2325 in order to understand their structm-es in the buman genome and to construct human allelic ladder, which is necessary for forensic DNA typing. In orderto evaluate the forensic applicability of Dl0S2325 and to construct a preliminary database, the genotype distributions and allele frequencies in three major ethnic groups were investigated The population saillples included Caucasians (Gemlans), Africans (African Americans), and Asians (Chinese). A total of 520 samples from unrelated individuals was analyzed by Amp-FLp. An example of each allele and new alleles were sequenced Anele determination was carried out by comparison with a sequenced human allelic ladder made in-house. This pentanucleotide STR provided easily interpretable results. A total of 15 alleles was found in our population samples ThTee new alleles were observed and named as alleles 19 and 21 based on the number of repeat motifs, While allele 19 can be divided furdier into two alleles. 19a and 19 according to analysis 0f the sequence No evidence of deviation from Hardy-Weinberg equilibfimn was observed in 64 confimled father/motber/child triplets no mutation event was observed. Using a maximmn likelihood method. the mutation rate was indirectly esthnated as 2.5