Arylsulfotransferase was stabilized for storage more markedly by covalent immobilization onto DEAE-cellulose or DEAE-Sephadex. The optimal pH, Km for sulfate donor and thermostability of covalently immobilized arylsulfotransferase were similar to those of the free enzyme. Tyrosine-containing peptides such as cholecystokinin-8-nonsulfate, tyrosine methylester and (Leu)enkephalin as acceptor substrates were effectively sulfated by the immobilized enzyme.