The merging of urethane and polyester technologies results in hybrids which have combinations of propeties that are superior to either of the polymers alone. The unique properties in the cured resin were obtained since urethane chains and the styrene chains in the hybrid resin could be crosslinked by trimethylol pentane(TMP) and divinyl benzene(DVB), respectively, to have improved properties with complex morphologies. Tensile strength of hybrids showed maximum(78MPa) at DVB 10wt%(for UPE alone, 45.5MPa). Impact strength increased as urethane content was increased in the hybrid resin due to the energy absorption of rubbery particles with slight decrease of tensile strength. The hybrid resins which consist of lower molecular weight UPE polyol(Et04) showed higher tensile strength but lower impact strength than those which consist of higher molecular weight UPE(Et12). Dynamic mechanical analysis(DMA) showed the phase separtion when poly(tetramethylene ether) glycol(PTMG) was used as a polyol in the urethane chain due to its incompatibility with propylene glycol in the UPE matrix, so that the impact strength was higher than when polypropylene glycol(PPG) was used. The forming of hybrids improved relative thermal stability indicated by the onset point in thermogravimetric analysis(TGA). Scanning electron microgragh(SEM) showed finely dispersed microdomains of rubber particles and the fracture surface showed shear yielding.