Hairtail, Trichiurus lepturus, ecologically warm water fish species, belonging to family Trichiuridae, widely distributed on the coast of the West Sea, South Sea and Jeju island in the Korean Peninsula and the several sea areas in China under the natural ecosystem. The food consumption of this species has increased considerably in various types of restaurants (including restaurants specializing in serving hairtails roasted and soy-sauce glazed cutlass fish with radish or other vegetables) for a long time. However, in spite of their economic and scientific consequences, a little information currently exist regarding the physiological and ecological levels only of hairtail species in Korea. Only the biological fisheries feature, distribution and migration of hairtail, Trichiurus lepturus, in Korean waters were in vestigated (Kimatal, 1998; Parketal, 2002). Lately, imported hairtail have been changed into endemic hairtail because of high margin. In the present study, to elucidate the genetic distances and differences among geographical hairtail, Trichiurus lepturus, populations, we performed a clustering analysis of two hairtail populations collected from Korea and China. Muscle tissues were collected separately from hairtail, Trichiurus lepturus, in dividuals from Korea in the Yellow Sea and China in the East Sea, respectively. RAPD-PCR analysis was performed on DNA samples extracted from a total of 44 (specimen numbers for duplicate experiments) individuals using eight arbitrarily selected primers of two decades of different decamer primers. Hairtail muscle was collected in sterile tubes, immediately placed on dry ice, and stored at －40℃ until the genomic DNA extraction. Genomic DNA was extracted and purified under the conditions described previously (Yoon and Kim, 2004). The degree of variability was calculated by use of the Dice coefficient (F), which is given by the formula: F = 2 nab/(na+nb), where nab is the number of bands shared between the samples a and b, na is the total number of bands for sample a and nb is the total number of bands for sample b (Jeffreys and Morton, 1987; Yoke-Kqueen and Radu, 2006). Euclidean genetic distances within- and between-populations were also calculated using the hierarchical dendrogram program Systat ver.10 (SPSS Inc., Chicago, IL, USA). The random primers OPA-07, OPA-20, OPB-14, OPB-15, OPB-17, OPB-18, OPD-16 and URP-07 showed common, polymorphic and specific bands produced using each primer to amplify genomic DNA isolated from the muscle of individuals. Accordingly, PCR analysis generated on the RAPD data showed that the geographic hairtail population from Korea in the West Sea was more or less separated from geographic hairtail population from China in the South Sea. The hierarchical dendrogram resulted from reliable four primers, indicating three genetic clusters composed of group 1 (Korean No. 1～11) and group 2 (Chinese No. 12～22). The genetic distances between two geographic populations ranged from 0.038 to 0.476. Individual No. 09 within hairtail population from Korea was genetically closely related with No. 06 (genetic distance = 0.104). The longest genetic distance (0.476) displaying significant molecular difference was also between individual No. 01 within hairtail population from Korea and No. 22 from Chinese. In the present study, RAPD-PCR analysis has revealed significant genetic distances between two hairtail population pairs. High levels of genetic polymorphisms and the existence of population differentiation between two hairtail populations showed RAPD-PCR approach is one of the suitable tools for individuals and/or population biological DNA studies.