A series of polymeric dyes wre synthesized by free radical addition polymerication of monomeric dyes. The 2-amino-5-mrecapto-1,3,4-thiadiazole was diazotized and coupled with various N-arlmaleimides to give monomeric dyes. All the polymeric dyes were characterized by elemental analysis, infrared spectroscopy, visible absorption spectroscopy, viscometry. and thermogravimetric analysis. Color and dyeing properties of the polymeric dyes were discussed by comparing them with those of the corresponding monomeric dyes. The dyeing performance of these dyes was assessed on nylon fiber. These dyes were found to give various color shades with good to very good depth and levelness on the fiber. The dyeing of the monomeric dyes showed moderate fastness to light and good to excellent fastness properties. The dyebath exhaustion and fixation on nylon fiber has been found to be good.