Abstract: To study the vslue of plasma prostaglandin E_2 (PGE2) in primary cancinoma of the liver (PHC), we have determined the level of plasma PGE2 in 30 PHC (including 22 metastasized and 8primary), 10 alcoholic liver disease, 39 cirrhosis, 30 normal persons. The result indicates that the increase of the level of the plasma PGE2 in PHC patients is very significant (P0. 001), and the increase of metastasized than primary is also significant (P0. 01), but in the two benign liver diseases the increase is not significant (P0. 05). We consider that there is some significance in early finding out the changing from ciihosis to PHC and controling the proliferation and transformation of PHC.