Macromolecular collagen components in normal liver and at the different stages of human liver cirrhosis were studied under various extraction conditions. The collagen content at the typical stage of liver cirrhosis was more than five-fold higher than that of the normal state. Pepsin-solubilized collagens extracted successively accounted for 90% of the total collagen and were subjected to determination of the collagen types by salt differentiated fractionation and SDS-polyacrylamide gel electrophoresis. Both type I and III collagens, especially the former, increased, reflecting enhanced total collagen with the progression of liver cirrhosis. The ratio of type I to type III was 1.02 - 1.22 in normal liver and at the early stage of liver cirrhosis, but increased to 1.58 and 1.60 at the typical and advanced stages of liver cirrhosis, respectively. At the early stage, the remarkable increase in type V collagen started much earlier than at the typical stage when the ratio of type I to type III changed. The enhancement of type V collagen may result from a cell proliferative phenomenon at the earlier stage of liver cirrhosis.