We have prepared new polyesters containing quadratic, nonlinear optical (NLO) active chromophores covalently incorporated into the main chain. In these polymers, the sequence of the chromophore units along the main chain is rigorously head to tail. All the polyesters are processable, both in the melt and in solution. For one polyester, a full second-order NLO characterization has been performed. An out-of-resonance d(33) coefficient of 21 pm/V at 1368 nm has been measured. (c) 2007 Wiley Periodicals, Inc.