The activity of enzymes of nitrogen and energy metabolisms from dogfish liver and a commercial preparation Catrex manufactured in the Scientific-Industrial Association "Adaptogen" (Tbilisi) was studied. The liver homogenate contains active glutamate dehydrogenase (GD), malate dehydrogenase (MD) and lactate dehydrogenase (LD) catalysing in vitro the reaction in both directions, as well as active glutamine synthetase, aspartate transaminase and alanine transaminase. These enzymes are also present in Catrex, but their activities are less. After 10-day storage of the liver homogenate and the Catrex preparation the enzymes slightly inactivated. Two isozymes of MD and four isozymes of LD were detected in the liver homogenate by polyacrylamide gel electrophoresis. In Catrex the two MD isozymes and only three LD isozymes were found.