Three novel thiocyanato-bridged polynuclear cadmium(II) complexes, [Cd(HL1)(NCS)(2)(mu(1,3)-NCS)](n) (1), [CdL2(mu(1,3)-NCS)(2)](n) (2), and [CdL3(mu(1,3)-NCS)(2)](n) (3) (L1=N-methyl-N'-(1-pyridin-2-ylmetbylidene)ethane-1,2-diamine, L2=2-(cyclopropyliminometbyl)-6methoxyphenol, L3=2-(cyclopentyliminomethyl)-6-methoxyphenol), have been synthesized and structurally characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Each cadmium(II) atom in the complexes is in an octahedral coordination. The urease inhibitory activities of the complexes were evaluated. All of them showed potent inhibitions against jack bean urease.