The effects of intravenously administered of high concentration of taurocholic acid (TCA) on $alpha$-D- and $eta$-D-mannosidase activities in rat liver lysosomes were studied. These liver lysosomal enzymes, and serum lysosomal $alpha$-D- and $eta$-D-mannosidase isozymes activities were determined in experimental rats with common bile duct ligation (CBDL). The liver lysosomal $eta$-D-mannosidase activity as well as the serum lysosomal $alpha$-D- and $eta$-D-mannosidase isozymes activities were found to be significantly increased in the CBDL plus TCA injected group than in the control group such as CBDL alone group. However, the liver lysosomal $alpha$-D-mannosidase activity was found to be significantly decreased in the CBDL plus TCA injected group. The above results suggest that TCA repress the biosynthesis of the lysosomal $alpha$-D-mannosidase and induce the biosynthesis of the lysosomal $eta$-D-mannosidase in the liver. And that the elevated serum lysosomal $alpha$-D- and $eta$-D-mannosidase isozymes activities are most likely due to increased hepatocyte membrane permeability caused by TCA mediated liver cell necrosis.