Three mammalian and eight non-mammalian arylsulfatases were investigated for their activities toward tyrosine-O-sulfate (TyrS) in peptides. None of the mammalian arylsulfatases exhibited detectable activities toward TyrS-containing peptides. Of the non-mammalian arylsulfatases tested, Types VII, VIII, and H-1, 2, and 5 displayed strong activity on endo-TyrS residues. The prokaryotic sulfatase, Type VI, was active only on free TyrS and N-terminal TyrS of Leu-enkephalin. All the sulfatases were active on p-nitrophenyl sulfate and p-nitrocatechol sulfate.