Monomeric dyes have been synthesized by the diazotization of 2-amino-3,5-bis(ethoxycarbonyl)-4-methylthiophene and coupled with various substituted N-arylmaleimides. The polymeric dyes have been derived fi om monomeric dyes by the free radical addition polymerization. The polymeric dyes are characterized by intrinsic viscosity, molecular weight by VPO and thermogravimetry. Monomeric and polymeric dyes also have been characterized by their IR spectra and elemental analysis. All the dyes are applied on nylon and polyester fibres as a disperse dye and their dyeing properties are studied.