A number of biologically: active nickel (ll),copper(ll) and zinc(1I) chelates with a novel thiazole derived sa1icylaldehyde having the same meta1 ion but different anions, e.g., nitrate. sulfate, oxalate and acetate. have been synthesized and characterized on the basis of their physical, spectra1 and analytical data. In order to evaluate the role of anions on their antibacterial properties, the ligand and its synthesized meta1 chelates with various anions have been screened against bacterial species Escherichia coli. Pseudomonas, aeruginosa and Slaphylococcus aureus. The title studies have proved the role of anions in enhancing the antibacterial properties.