The purpose of this study was to investigate the relationship between Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene and complex phenotypes such as blood pressure, body compositions and bone parameters in young men about 20 years, and to collect the fundamental data in designing the exercise program. Eighty healthy young men including 41 controls and 39 athletes were recruited, Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene was genotyped by PCR-RFLP method. By association study, there were no significance in genotype and allele frequencies of Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene between controls and athletes, respectively (p>0.05). When the relationship between physiological parameters and Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene was tested, this polymorphism was significantly associated with 3th lumber and left femoral neck Z-score values in controls (p<0.05), but these associations were not detected in athletic groups (p>0.05). It is likely that Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene is a genetic marker for the bone mineral density index in young men, but environmental factors such as exercise modify the significant effect of this polymorphism. Thus, our results suggest that Trp64Arg polymorphism in the ${eta}_3$-adrenergic receptor gene may be applicable as a predictive marker for osteoporosis in Korean young men, and regular exercise may prevent the disadventageous effect of this polymorphism for bone mineral density in male athletic group.