C-terminal peptide of procollagen I, N-terminal peptide of procollagen III, collagen IV and serum prolyl hydroxylase were measured in 100 patients with cirrhosis and 71 patients with noncirrhotic chronic liver disease. Patients with cirrhosis had significantly higher mean values of prolyl hydroxylase, collagen IV, N-terminal peptide of procollagen III and C-terminal peptide of procollagen I as compared to noncirrhotic patients. This difference was maintained for collagen products even after stratification for alcohol intake, although all markers of fibrosis were higher in alcoholics. Stepwise logistic regression analysis showed that collagen IV, and N-terminal peptide of procollagen III were independently associated with cirrhosis. Receiver-operating characteristic (ROC) curves showed that collagen IV and N-terminal peptide of procollagen III perform more efficiently than C-terminal peptide of procollagen I and prolyl hydroxylase in identifying cirrhosis.