The orientational relaxation of the NLO-phores in polyamides based on 2’,5’-diamino-4-(dimethylamino)-4’-nitrostilbene (DDANS) and linear aliphatic diacid chlorides was investigated at different temperatures below the glass transition by the decay of the nonlinear optical susceptibilities of corona-poled thin films. The time dependence of the decay was found to be well represented by the Kohlrausch-Williams-Watts stretched exponential function. The temperature dependence of the decay could be correlated with the glass transition temperature T-g using a normalized relaxation law with (T-g - T)/T as the relevant scaling parameter. For one of the polyamides, showing a T-g of 176 degrees C, no decay of the NLO coefficient was observed at 25 degrees C within 8 months. For the purely orientational relaxation at 80 degrees C a relaxation time of significantly over 10 years could be estimated. As shown by UV-vis spectroscopy, the long-term stability of the new polyamides is restricted by the limited thermal stability of the NLO-phore. The polyamides investigated exhibit an enhanced orientational stability, as can be seen from the aging data. They represent a new approach to the design of polymers with large. and stable second-order nonlinear optical properties, where the nonlinear optical units are fixed in the polymer backbone with their dipole moments oriented transversely to the main chain.