Isoenzymes of the liver tissue lactate dehydrogenase (LDG) were examined in 37 patients with micro- and macronodular cirrhosis. LDG isoenzymes were studied by histochemical and cytophotometrical methods, electrophoresis in polyacrylamide gel, densitometry. The results were treated statistically. Uneven (mosaic) distribution of LDG activity in hepatocytes was observed in hepatocirrhosis. Different hepatocytes and fibroblasts had dissimilar sets of LDG isoenzymes. Anodal isoenzymes showed a higher activity in the bile duct epithelium. Cathodal isoenzymes in hepatocytes were localized mostly near the external cell membrane and the nuclear membrane. Micronodular cirrhoses are characterized by an increased activity of LDG2 and LDG3 and a decreased activity of LDG5 in the liver tissue. Macronodular cirrhoses are characterized by a decreased activity of LDG1 and LDG3 and an increased activity of LDG5. In the presence of hepatocyte insufficiency the activity of LDG1 decreased. Changes in the liver tissue LDG isoenzymes profile is due to a number of degenerative and regeneratory lesions typical of the cirrhotic process. The determination of the profile of the liver tissue LDG isoenzymes is important for the establishment of the type of cirrhosis, the degree of hypoxia, the intensity of regeneration processes, and the effectiveness of the therapy given to the patient.