To determine whether alterations of the carbohydrate moiety of human alpha 1-acid glycoprotein constitute a marker of hepatic damage we studied purified alpha 1-acid glycoprotein from healthy individuals and two groups of patients with benign liver diseases: alcoholic cirrhosis and acute viral hepatitis. The results indicate: (1) increased concanavalin A-non reactive forms in cirrhosis and hepatitis, (2) a markedly increased proportion of fucosyl residues in all cirrhotic and some hepatitis patients. Although hyperfucosylation is generally considered to be a tumor marker, the observation here in the two benign liver diseases indicates that an increased fucosyl content should be considered as a more general expression of pathological glycoconjugate metabolism.