This review discusses nonlinear optical (NLO) polymeric materials. As an example of a second-order NLO material, a novel copolymer with a diazo dye attached is investigated. The second-order NLO coefficient chi(2) of the copolymer reaches 1.0 X 10(-6) esu, which is 7 times larger than that of LiNbO3. A third-order NLO coefficient chi(3) larger than 10(-10) esu is obtained for polymers where NLO dyes are introduced into the polymer backbone. The optical transmission loss of these polymers is revealed to be around 2 dB/cm. As these polymers can be formed into channel waveguides using the photo-bleaching technique, they show promise for use in NLO devices because of their processability, transparency and large optical non-linearity.