The changes in lysosomal enzyme activities in rat liver after partial hepatectomy were studied with the whole liver and isolated hepatocyte suspension. The activity patterns of enzymes were different between the stages before and after mitosis, and also between the two cell types of hepatocytes and non-hepatocytes in the liver. Increase of enzyme activities, especially of acid ribonuclease, in the premitotic stage suggests that the lysosomes may participate in the cell division during liver regeneration
