The original recommendations concerning the nomenclature of metallothionein were made by the plenum of the First International Meeting on Metallothionein and Other Low Molecular Weight Metal-binding Proteins in 1978 (Nordberg and Kojima, 1979). The present revised version includes amendments to these recommendations as adopted by the Committee on the Nomenclature of Metallothionein appointed at the General Discussion Session of the Second International Meeting on Metallothionein and Other Low Molecular Weight Metal-binding Proteins in 1985.