The alterations of ALP of the serum have been studied among a control, patients with diabetes mellitus, patients with liver cirrhosis, and patients with liver cirrhosis accompanied with diabetes mellitus. The average activity of serum ALP of each group was 2.0 Bodansky units(U) in the control, 2.6 U in patients with liver cirrhosis and 5.5 U in patients with liver cirrhosis accompanied with diabetes mellitus. The values of any two groups of these were statistically significant. Electrophoretic separation of the ALP isoenzymes of these groups indicated that these differences were due to the change in intestinal component of total ALP in the serum. These data indicated that intestinal ALP activity in the serum was influenced by the metabolic disorder of glucose whether or not liver cirrhosis existed. And it also indicated that increase in intestinal ALP was exaggerated in the serum of the patients with liver cirrhosis accompanied with diabetes mellitus as compared with the patients with liver cirrhosis without diabetes mellitus.