Lipids in the separable lean of raw and cooked beef were determined, as part of an extensive cooperative study to provide current data on the nutrients in retail cuts and quality grades. Paired cuts from right and left sides of 8 carcasses were analyzed raw and cooked; an additional 172 raw cuts, each from a different carcass of prime, choice, or good grade, were also analyzed raw. In raw separable lean beef, representative values were as follows: total fat minimum, 3.2% in round top round steak, good grade, total fat maximum, 14.6% in rib roast large end, prime grade; cholesterol minimum, 49.9 mg/100 g in round eye round roast, good grade, cholesterol maximum, 68.1 mg/100 g in brisket flat half boneless, good grade; linoleate minimum, 1.6% in brisket flat half boneless, choice grade, linoleate maximum, 5.3% in round top round steak, good grade; saturated fatty acids minimum, 37.9% in brisket point half boneless, prime grade, saturated fatty acids maximum, 48.8% in loin tenderloin steak, choice grade; P/S ratio minimum, 0.04 in brisket flat half boneless, choice grade, P/S ratio maximum, 0.16 in round tip roast, left, good grade; trans-monoene minimum, 1.3% in round top round steak, choice grade, trans-monoene maximum, 4.4% in rib roast large end, good grade. Cooking caused a loss of fat from the cuts as a whole, but caused an increase in the fat in the separable lean, ranging from 0.75% in the round eye round roast to 3.26% in the chuck arm pot roast. Estimates of the true retention of fat averaged 125 ± 2.0%, of volatiles 59 ± 9.0%, and of cholesterol 106 ±.9%. Cholesterol in the raw separable lean was positively correlated with fat ( r = 0.58) and negatively correlated with nonfat solids ( r = −0.53).