Ultracentrifugal separation and analysis of chylomicron, very low, low and high density lipoproteins in the sera from patients with liver metastasis of cancer were carried out. Studies were made on the relationship between lipoprotein and alkaline phosphatase (Al-P) on cellogel electrophoresis. 1) On cellogel electrophoresis, the serum Al-P isozyme of a patient with liver metastasis was divided into Bands I and II. Band I which corresponds to macromolecular Al-P is characteristic of liver metastasis. 2) Band I was found only in high density lipoprotein (HDL) fraction. This result indicates that the density of Band I is very close to that of HDL. 3) The electrophoretic mobility of macromolecular Al-P was the same with that of HDL. 4) No relationship was found between Band II which corresponds to Al-P with a small molecular weight and lipoprotein. 5) By treatment with receptor destroying enzyme of the serum, the electrophoretic mobility of the lipoproteins remained unchanged. Band I, however, was detached from HDL and moved toward the origin. These results suggest that Al-P bands contain a large quantity of sialic acid.