The N-linked sugar chain structures of human hepatic, intestinal, and placental alkaline phosphatases (ALPs) were studied comparatively by chromatography on various lectin columns in combination with digestion by several kinds of exoglycosidases. The sugar chain structures were organ specific. On the basis of these organ-specific structures, we investigated serum ALP using a Neu5Ac(alpha)2-->6Gal(beta)1-->4 GlcNAc-specific Trichosanthes japonica agglutinin-I (TJA-I)-Sepharose column to clarify whether the level of TJA-I-binding serum ALP activity can be used as an indicator to discriminate one form of chronic liver disease from another. Levels of TJA-I-binding ALP in serum were higher in cases of liver cirrhosis and hepatocellular carcinoma than in chronic hepatitis (P < 0.01). The levels of TJA-I-binding ALP in serum did not change significantly after transcatheter arterial embolization, and the amounts of TJA-I-binding ALP activity in noncancerous cirrhotic liver tissues were higher than those in cancerous liver tissues derived from hepatocellular carcinoma patients, indicating that the TJA-I-binding ALP is mainly derived from cirrhotic liver tissues rather than cancerous liver tissues. These results indicate that analysis of the levels of TJA-I-binding ALP in serum is clinically useful for differentiating liver cirrhosis from chronic hepatitis and that altered sugar chain expression in ALP occurs mainly in liver cirrhosis.