The male WBN/Kob rat is an animal model of chronic pancreatitis and spontaneous diabetes. Here, we performed a kinetic study of alkaline phosphatase (ALP) in WBN/Kob rats. The level of serum ALP activities in the WBN/Kob rats was three times higher than that of the control group ( p <0.001). Specific ALP activities in bone tissues or the ileum increased significantly ( p <0.01 and p <0.05, respectively). By 4-20% gradient polyacrylamide gel electrophoresis, serum ALP isozymes were separated into two bands. One was heat-unstable, showing the same mobility as an ALP preparation from bone tissue, and the other was heat-stable. We considered these isozymes to be bone-type and intestinal-type ALPs, respectively, and both of them were enhanced in the WBN/Kob rats. These results demonstrate the enzyme kinetics of ALP isozymes in WBN/Kob rats, and further studies will be necessary to reveal the association with diabetes.