The objective of this research was to investigate the effect of marbling scores on carcass grade factors, physico-chemical and sensory traits of Hanwoo. Data used in this study were collected from 73,316 carcasses obtained at the Nonghyup Seoul slaughterhouse in 2009 and 271 cuts of M. longissimusdorsi were analyzed to estimate beef qualities. As the marbling scores increased, backfat thickness was linearly increased (p<0.05) in cows (9.51 mm-14.69 mm) and steers (8.71 mm-14.23 mm). As the marbling scores increased, maturity of cows was increased and meat color, texture and quality grade improved for all genders. With increase of the marbling scores, crude fat contents (3.07%-26.70%), water holding capacity (52.09%-58.66%), L * value (34.08-41.97) were significantly increased (p<0.05) and Warner-Bratzler shear force was linearly decreased (p<0.05) from 8.58 kg to 2.60 kg. The increase of crude fat contents had the similar interval with the increase of marbling scores from 1 to 6 but it is sharply increased from marbling score 7. There was no difference observed on pH 24 (5.50-5.66), protein contents (19.57%-21.15%) among the marbling scores. Marbling score was significantly correlated with live weight (r=0.29) in cows, loineye area (r=0.35) in steer, and overall acceptability of panel scores (r=0.67) (p<0.01).