Chromogranin A is a cellular marker forneuroendocrine tumors. Elevated levels of chromogranin A are also found in patients with cancers of epithelial origin when neuroendocrine differentiation occurs, which is associated with a poor prognosis. We investigated the prevalence of serum levels of chromogranin A in patients with primary liver cancer. Seventy-nine patients (65 males, mean age 67.6 years, range 48-88 years) with liver cirrhosis and hepatocellular carcinoma were studied. The etiology of cirrhosis was identified as due to hepatitis C virus infection in 47 patients, to hepatitis C virus and alcohol in 7, to alcohol alone in 14, to hepatitis C and B virus in 2, and to hepatitis B virus alone in 4. Of the remaining patients, 2 suffered from hemochromatosis and 3 had cryptogenic cirrhosis. According to the Child-Pugh's score, 54 patients belonged to class A, 22 to class B, and 3 to class C. The concentration of chromogranin A was measured in serum with a commercial solid-phase two-site immunoradiometric assay. Elevated serum levels of chromogranin A were found in 32 of 79 patients (43%). Levels over 600 ng/ml were present in 7 of 76 patients (9.2%), all of whom had very high serum levels of alpha-fetoprotein. Hence, elevated serum levels of chromogranin A are present in over one third of patients with hepatocellular carcinoma. It is therefore possible that some hepatocellular carcinomas could acquire a neuroendocrine differentiation. We propose further studies to ascertain whether serum levels of chromogranin A are useful as a prognostic marker for hepatocellular carcinoma as in prostate cancer.