A patient who developed valproate-associated hepatotoxicity had significantly lower serum levels of total protein, albumin and selenium than the controls. This study shows that with the beginning of the hepatic coma metallothionein (MT) appeared in the serum mainly in the form of Zn-thionein, which altered the Zn distribution pattern of the serum in a characteristic manner. HPLC-ICP3 was successfully applied to the simultaneous speciation of elements and characterization of MT by the use of one gel permeation column.