Upon extracting phosphatides from blood which has been shaken for a few hrs. with labelled (radioactive) Na phosphate, a minute % of the phosphatides is found to be labelled. Replacement of normal blood with lipemic blood does not noticeably influence the % found to be labelled. When, however, upon investigating by the same method blood which percolated an isolated cat liver, lipemic blood is found to contain more labelled phos-phatide than normal blood. The phosphatide extracted from the tissue of the percolated liver shows a similar behavior. When using blood on the average 1.5% of the liver phosphatides were found to be labelled, in the case of lipemic blood the % was found to be 2.7.