In order to clarify the biochemical features of metastatic tissues into the liver of human cancerous cells, 12 of primary cancerous tissues and 3 of metastatic tissues of the large intestinal cancer, 6 of primary cancerous tissues and 2 of metastatic tissues of the gastric cancer, and 3 of primary cancerous tissues and 3 of metastatic tissues of malignant insulinoma were studied lipid-chemically. Cancerous tissues and metastatic tissues into the liver were collected by biopsy or surgical operation. From each tissue, the total lipid was extracted and one part of the total lipid was separated into phospholipid and triglyceride by TLC. Then, the fatty acid composition and the fatty acid content of each lipid fraction were measured by GLC. The most remarkable findings were recognized in the phospholipid fatty acid composition of the tissues. Namely, the percentage values of C_14:0 and C_16:1 were larger and that of C_20:4 was smaller in metastatic tissues than those of gastric primary lesions. As for the large intestinal cancer, the percentage value of C_18:1 was smaller and that of C_18:2 larger in metastatic tissues than those of primary lesions. In the malignant insulinoma, the percentage value of C_18.0 was larger in metastatic tissues than that of the primary lesions.