The objective was to quantify the naturally occurring free L-Carnitine (FC), acylated (AC), and total carnitine (TC) in skeletal muscle of Angus beef cattle. These data then were correlated to the yield grade (YG) and marbling scores (MS) of the same samples of longissmus dorsi muscles at 12th rib were collected from 1085 purebred Angus bulls, steers, and heifers from Iowa and California and used to quantify different the forms of carnitine. The spectrophotometric and enzymatic quantification of the different carnitines demonstrated that concentration of FC ranged from 2.12 to 6.32 ymol/g of beef and averaged 3.77 y 0.80 ymol/g of beef. Also, the AC concentration ranged from 0.05 to 1.61ymol/g and averaged at 0.71 y 0.17 ymol/g of beef. Similarly, the TC ranged from 2.60 to 7.28 ymol/g of beef and averaged at 4.48 y 0.88 ymole/g of beef. Overall beef from male Angus beef contained higher FC (P = 0.01) and tended to have higher TC (P = 0.09) than that of beef from female. The AC, however, tended to be higher (P = 0.08) in beef from female Angus beef cattle. Additionally, the yield grade (YG) was greater in female Angus beef cattle. The marbling score (MS), however, tended to greater (P = 0.06) in beef from male Angus beef cattle compared with that of beef from the female. These data suggest that increased carnitine concentration in beef is associated with increase YG and MS of beef from Angus cattle.