In order to explore the useful genetic marker(s) influencing the athletic performance of throwers, we performed a kind of case-control study genetic association study using the rs8111989(NcoI, A/G) polymorphism in the muscle-specific creatine kinase(CKMM) gene as a candidate gene. A total of 160 unrelated subjects including controls(n=70) and thrower (n=90) were recruited in this study, and total genomic DNA isolated from their saliva. The analysis of A/G polymorphisms in CKMM gene from their total genomic DNA was performed by using SNaPshot method in automated machine. By the result of genotype analysis, there was the significant differences in both genotype and allele frequencies of the A/G polymorphism in CKMM gene between controls and throwers, respectively(p.05). Especially, the frequencies of GG genotype and G allele in this genetic polymorphism showed the significantly higher frequencies in throwers than in controls, respectively. Thus, this genetic polymorphism may be one of useful genetic markers influencing the athletic performance in throwers. However, because athletic performance indicate the polygenic and multifactorial trait, the further studies using other genetic polymorphisms in more candidate genes will be required.