Serum alkaline phosphatase isoenzyme pattern of liver disease in adult age have been studied using cellulose acetate electrophoresis on New Dry Titan IV I.E plate and compared with the serum electrophoretic mobility of each protein components. The results were: 1) Seperated were six fractions corresponding to albumin band, alpha 1 (fast liver), alpha 2 (liver), between alpha 2 and beta (bone), between beta and gamma (intestine), and diffuse band between gamma and application point of the electrophoresis(Pa). 2) Liver band corresponding to alpha 2 appeared in all normal control group and diseases. And it have been suggested that alkaline phosphatase may be originated from liver in adult age. 3) Characteristic band corresponding to albumin fraction appeared in hepatocellular carcinoma (13/19), and obstructive jaundice (9/18) due to cholelithiasis and pancreatic carcinoma. 4) Fast liver corresponding to alpha 1 have been demonstrated in the same diseased group that showed albumin band, particularly all of six cases of pancreatic carcinoma. 5) Bone (α2/β) and intestine (β/r) fractions were less often demonstrated in this study. 6) Pa (gamma to application point) band have been demonstrated in two out of six cases of the pancreatic carcinoma. It is therefore, summarized that further studies are required to make use of alkaline phosphatase isoenzyme pattern in a routine clinical tests differentiating liver disease.