The type III procollagen aminopeptide (sPIIIP) serum levels were measured in 197 patients with liver disease and were correlated with morphological and serological alterations and with alcohol drinking habits. The sPIIIP levels resulted significantly increased in 51% of 43 patients with untreated chronic active hepatitis (CAH), in 61% of 36 patients with CAH plus cirrhosis, in 69% of 26 patients with inactive cirrhosis, in 4 out of 8 patients with alcoholic steatosis and fibrillogenesis, but remained unchanged in 38 cases of alcoholic steatosis plus siderosis and in 13 cases of chronic persistent hepatitis. A correlation between sPIIIP levels and the histological pattern of fibrosis could not be demonstrated in a single type of fibrotic liver disease and no differences were found between alcoholic and non-alcoholic patients. We agree upon the opinion that high sPIIIP levels may identify liver fibrogenic activity, but this test needs further technical improvements before it could be widely used in the clinical practice.