Low density lipoprotein in Ehrlich tumor bearing mice was studied on lipids in serum and Organs, and which were compared with those of normal mice by means of disc electrophoresis, biochemical analysis and thin-layer chromatography. The mobility of tumor bearing mice low density lipoprotein (L D L) in electrophoresis was smaller than that of normal mice L D L. The quantity of phospholipid to protein was decreased in tumor bearing mice L D L than normal. The ratio of phospholipid to cholesterol in serum and liver was decreased in tumor bearing mice than normal. On the structure of phospholipids, the content of lecithine in tumor bearingmice L D L reduced by half than normal