The prognostic value of the aminoterminal propeptide of type III procollagen (P3NP) was investigated in 63 patients with primary biliary cirrhosis (PBC) followed for up to 87 months. No patient with an initially normal serum P3NP level died during the study; survival was significantly worse with increasing serum P3NP levels. Cox multivariate analysis confirmed that serum P3NP was an independent prognostic variable. Positive correlations were found between serum P3NP and histological stage, pericellular fibrosis, piecemeal necrosis, and serum concentrations of alanine aminotransferase and aspartate aminotransferase. Raised P3NP levels also correlated with the degree of cholestasis as evaluated by serum bilirubin, serum alkaline phosphatase, and copper binding protein deposition in the liver. Serum P3NP is of prognostic value because it reflects the major pathophysiological features of PBC.