Lysosome are subcellular particles in which several acid hydrolases of various specificities are localized. The role of lysosome in cellular physiology and pathology has drawn considerable recent attention by several groups of investigators. The purpose of this study was to investigate the activities of lysosomal enzymes--acid phosphatase, beta-glucuronidase, N-acetyl-beta-glucosaminidase--in hepatic disorders. 1) The serum levels of beta-glucuronidase and N-acetyl-beta-glucosaminidase were significantly elevated in patients with diseases of the hepatobiliary system. 2) N-acetyl-beta-glucosaminidase activity in urine specimens from patients with diseases of the hepatobiliary system was found to be significantly higher than in urine specimens from normal adults. 3) Male albino rats of 150 approximately 200 g body weight were used. CCl4 was injected intraperitoneally (dose 0.1 ml of CCl4 per 100 g body weight twice a week for eight weeks). The free activities of lysosomal enzyme were increased and high free/total activity ratios were found in the liver lysosomal fraction of CCl4 intoxicated rats. The results of these experiment indicated that the membranes of lysosome were more permeable to their enzymes, and the release of these enzymes were found in the experimental fatty liver by CCl4. 4) Corticosteroids and chloroquine stabilized rat liver lysosome in vitro from the labilizing influence of incubation at 37 degrees C. 5) The administration of chloroquine to CCl4 intoxicated rats did not cause any well-expressed stabilization of lysosomes. 6) When alpha-Tocopherol was administrated to CCl4 intoxicated rats, the decrease of bound activity and increase of free activity in lysosomal fraction, and increase of acid hydrolases, GOT and GPT in serum were inhibited.