2,5-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (2) was prepared and condensed with 2,4-toluenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate and 1,6-hexamethylenediisocyanate to yield novel T-type polyurethanes 3-5 containing the NLO-chromophore 2,5-dioxynitrostilbenyl group, which constitutes a part of the polymer backbone. Polymers 3-5 were soluble in common organic solvents such as acetone and DMSO. Polymers 3-5 showed a thermal stability up to 280degreesC in TGA thermograms with T(y)s of 79-159degreesC in DSC thermograms. The SHG coefficients (d(gg)) of poled polymer films were around 5.4 x 10(-9) esu, and they exhibited greater thermal stabilities of dipole alignments even at 10degreesC higher than T-g due to the partial main chain character of the polymer structure.