The purpose of this research was to study the effects of feeding TMR (total mixed ration) dietary citrus by-products on nutritional composition and palatability of Hanwoo loin. Samples for the experiment consisted of Hanwoo loin that was not fed citrus by-products (TMR-0) and Hanwoo loin that was fed citrus by-products during fattening periods (TMR-1). The control (TMR-0) Hanwoo loin was fed by general practical feeding (roughages and concentrates were fed separately); the TMR-1 Hanwoo loin was fed identically to TMR-0 until 17 months yearling, but fed citrus by-products for 10 months after then. The levels of the moisture, crude protein, crude ash, cholesterol, Mg, K, vitamin $B_1$, vitamin $B_2$, total amino acids ($17.81{sim}17.98%$), and total free amino acids ($139.46{sim}149.15mg/100g$) were not significantly different between TMR-0 and TMR-1. The contents of the crude fat, Ca, and Na of TMR-1 were greater than those of TMR-0 (p<0.05). Oleic acid ($45.01{sim}49.38%$) was the most abundant anions unsaturated fatty acid while palmitic acid ($26.52{sim}28.39%$) was tile most abundant saturated fatty acid in both groups. In case of sensory scores, taste, flavor, and juiciness were not significantly different between TMR-0 and TMR-1. However, tenderness and palatability preference of TMR-1 were higher than those of TMR-0 (p<0.05).