Patients with chronic viral hepatitis and cirrhosis often have elevated serum alpha-fetoprotein (AFP) values, the causes of which are unclear. We studied 81 patients with chronic hepatitis C and the relationships of serum AFP and alanine aminotransferase (ALT) values, hepatic histologic features, and hepatocyte proliferation activity scores. Twenty-two patients had nil to mild fibrosis, 34 had moderate fibrosis, and 25 had marked fibrosis-cirrhosis. The mean serum AFP value was significantly greater in patients with more fibrosis. Serum ALT values were slightly greater in the marked fibrosis-cirrhosis patient group. The differences in the HAI and in hepatocyte MIB-1 scores were not significant. Among all patients, increasing serum AFP values significantly correlated with increasing ALT values. However, there were no significant correlations with serum ALT or HAI and serum AFP values. There was no association between serum AFP values and immunohistochemical staining for AFP within hepatocytes. These results suggest that elevated serum AFP values are the result of altered hepatocyte-hepatocyte interaction and loss of normal architectural arrangements. The presence of marked fibrosis or cirrhosis, a state of significant altered hepatocyte architecture, may be the underlying cause of increased serum AFP, rather than necrosis or active regeneration.