C-13 nuclear magnetic resonance spin-lattice relaxation times (T-1) and nuclear Overhauser enhancement factors C-13{H-1} (NOEf) have been measured on solutions of poly(ethylene terephthalate) (PET), poly(ethylene isophthalate) (PEI) and poly(ethylene isophthalate-co-terephthalate) (PEIT) in d(2)-tetrachloroethane. The T-1 and NOES values are well described by a log X(2) distribution of correlation times, while the isotropic model appears to be inadequate. The average correlation times (tau(0)) and the distribution parameters (p) of carbons and protons show features that are explained by invoking rotations and/or oscillations of terephthalic and isophthalic rings around the C1-C4 axis.