Four cases of chronic hepatitis associated with high serum levels of alpha-fetoprotein (AFP) without hepatocellular carcinoma are reported. All showed transient elevations of serum AFP, with peak levels of 13,500, 8,000, 4,450, and 3,000 ng/ml shortly after aggravation resulting from liver function tests. Liver biopsies revealed severe parenchymal damage in all the cases with piece-meal necrosis, bridging necrosis or bridging fibrosis. In two of four cases, there was a lobular distortion. AFP stain by an immunoperoxidase method showed a positive result in surviving hepatocytes. Lectin affinity electrophoresis of AFP in the four cases, together with an additional 12 patients with chronic hepatitis and cirrhosis and 44 patients with hepatocellular carcinoma, all having AFP levels above 1,000 ng/ml, revealed that the chronic hepatitis patients had a benign pattern of AFP bands, in contrast with the pattern of hepatocellular carcinoma with increased proportions of lentil lectin-reactive AFP-L3 and/or erythroagglutinating phytohemagglutinin-reactive AFP-P4, indicating that the analysis of lectin reactivity of AFP has a great value in differentiating the benign and malignant conditions with increased serum levels of AFP above 1,000 ng/ml.