The aim of this study was to identify the polymorphism on fatty acid synthase (FASN) gene and its association with fat traits and fatty acid composition in Hanwoo. We genotyped a SNP (g.16024G${ ightarrow}$A) detected in Exon34 of FASN on 90 Hanwoo steers by PCR RFLP. A linear mixed model revealed an association of g.16024G${ ightarrow}$A with total body fat contents (P=0.006), while there is no significant effect between g.16024G${ ightarrow}$A and other traits (IMF, BF and fatty acid composition). Regression coefficient and $R^2$ of the SNP was -1.5 kg and 0.36 in this anslysis. Expecially, AA type of g.16024G${ ightarrow}$A bas a less amount of body fat (1.5 kg) than GG type of the SNP in Hanwoo. In conclusion, this study indicates an important role for FASN gene in determining body fat content in Hanwoo.