Collagenolytic activity has been measured in insoluble sediments of normal and CCl4-induced cirrhotic rat liver. Two techniques were used: in one assay, the insoluble liver sediments were incubated with a radioactively labeled exogenous substrate; in the other assay, the endogenous collagen present in the insoluble liver sediments served as the substrate. Animals in various stages of development of CCl4-induced cirrhosis were used. Results suggest that in rat liver cirrhosis collagenolytic activity assayed with both techniques appears to increase when expressed as weight of collagen degraded in 24 hr. On the other hand, when the data are corrected for the variable amounts of collagen present in the insoluble liver sediments and expressed as weight of collagen degraded in 24 hr per unit weight of total collagen incubated, collagenolytic activity is shown to be significantly decreased below the normal level and to remain so for prolonged periods.