C14 -labelled stearic acid was administered to cats (A) with hydrolyzed corn oil, (B) with unhydrolyzed corn oil and (C) with corn oil plus active glycerides. Only 3-12% of the lipids fed were recovered in the lymph. Fractionation showed that in all cases the total lipids were approx. the same, the glyceride fatty acids constituting 70-80% of the total fatty acids. The high specific activity of glyceride fatty acids indicate that the free fatty acids in the case of (C) had been used for the synthesis of the lymph glycerides. The phospholipid fatty acids were 4 times as active in case (A) as in (C). Possible explanations of these results are given.