A dilute-solution spin-lattice relaxation time study was performed on a bisphenol polycarbonate related to the polycarbonate of bisphenol A except the two methyl, isopropylidene unit is replaced by a cyclohexyl group. C-13 spin-lattice relaxation times were measured at three Larmor frequencies : 50.3, 75.4, 125.7 MHz. The motion of cyclohexyl ring is seen to be isotropic on the spin-lattice relaxation time scale even though cyclohexyl rings undergo slow conformational change. Cyclohexyl ring relaxation is caused by segmental motion and was well interpreted in terms of the Hall-Helfand correlation function. The apparent activation energies for cooperative and individual bond transitions were 17 and 22 kJ mol(-1), while the corresponding Arrhenius prefactors were 15 x 10(-13) and 5 x 10(-13) s. This cyclohexyl polycarbonate differs from many other polycarbonates in that the two phenylene groups are inequivalent, one being axial and the other equatorial relative to the cyclohexyl ring. This difference could be clearly seen in the low temperature C-13 spectrum at a Larmor frequency of 125.7 MHz. In addition to segmental motion, it was found the equatorial phenyl ring underwent anisotropic internal rotation which could be described by the Woessner model, while the axial phenyl ring underwent restricted rotational diffusion which could be described by the Gronski model. Since full anisotropic rotation was observed in bisphenol A polycarbonate and restricted anisotropic rotational diffusion was observed in norbornyl polycarbonate, a clear picture of the effects of substitution in the isopropylidene units on local dynamics is developing.