Experiments were conducted with mature male rats to determine the digestibility of pure stearic, palmitic, myristic and lauric acids and of the corresponding triglycerides. Each fatty acid was mixed in the proportions of 5, 10, 15, and 25% with pure olive oil, and each triglyceride was mixed in the proportions of 5 and 10%. The fat mixture constituted 5% of the diet. The following results were obtained: Stearic acid was very poorly absorbed at each level of intake, the approximate digestive coefficients ranging from 9.4 to 21%. Palmitic acid was utilized somewhat more efficiently than stearic acid, the approximate digestive coefficients ranging from 23.8 to 39.6%. Myristic and lauric acids were practically 100% digestible when the fat mixtures contained 5, 10, or 15% of either acid, but the digestibility was somewhat lower when the mixture contained 25% of acid. Tristearin was very poorly utilized, the approximate digestive coefficients being 6 and 8% when the fat mixtures contained 5 and 10% of the triglyceride. Tripalmitin was much more digestible than tristearin, the approximate digestive coefficients being 84 and 82% when the fat mixtures contained 5 and 10% of the triglyceride. Trimyristin and trilaurin were very thoroughly absorbed.