Polymer matrix dependence of polarized light-induced anisotropy of the push-pull azo dye, Disperse Orange 3 (DO3; NO2-C6H4-N=N-C6H4-NH2), was investigated by UV-Vis and polarized FTIR spectroscopies. The orientation factors obtained by these spectroscopic methods helped us to understand the dynamics of DO3 in polymers. In methacrylate polymers and polystyrene (PS), the trans forms of DO3 are apt to isomerize to cis forms by the motion of p-NH2-C6H4 group side, because the relative volume of the p-NH2-C6H4 group is considered to be small compared with that of the p-NO2-C6H4 group. The large photoinduced anisotropy of DO3 (trans and cis isomers) was found in poly(methyl methacrylate) (PMMA). The small free volume in PMMA is considered to inhibit the rapid rotational motion of DO3 molecules. The free volume provides the primary effect on the polarized light-induced anisotropy, but the local polarity effect of matrices cannot be ignored for the anisotropy of DO3. In the less polar PS with the larger free volume, the anisotropy for cia isomers depends on the motion of NH2 groups, which do not interact with polymers so much. (C) 2000 Elsevier Science Ltd. All rights reserved.