dipeptidyl hydroxamic acids (H-X-Gly-NHOH: X = amino acid residues) was synthesized, and the inhibitory activity against Jackbean and Proteus mirabilis ureases [EC3.5.1.5] was examined. A number of H-X-Gly-NHOH inhibited Jackbeanurease with an I50 of the order of 10(-6) M and inhibited Proteus mirabilis urease with an I50 of the order of 10(-5) M. The inhibition against Jackbeanurease was more potent