Alpha-amylases were purified from fasted rat livers to homogeneity by the consecutive three purification steps; fractionation by ammonium sulfate, ion-change chromatography and gel filtration. On the last step, the enzyme was eluted in the fractions after elution of cytochrome c. When liver from non-fasted rats were used, the liver amylase molecules formed a complex with glycogen, and the purification did not reach to homogeneity. The liver amylase activity was enhanced in a low blood glucose caused by fasting, suggesting that the liver amylase might participate partially in glycogen metabolism. In contrast, the enzyme activity in a spontaneous diabetic rats (BB rats) was lower in high blood glucose than that before the diabetic onset. There are no remarkable characteristics between the amylases obtained before and after the onset. However, the reduced activity in diabetic rats might be due to an inactivation of liver amylase, which was triggered by glycation, resulting in a partial breakdown of the amylase molecule.