The miscibility of polycarbonate (PC) with poly(methyl methacrylate-co-cyclohexyl methacrylate) (PMCHM) and with poly (methyl methacrylate) (PMMA) was studied by nuclear magnetic resonance (NMR) H-1 spin-lattice relaxation time in the rotating frame (H-1 T1rho), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). A blend of PC/PMCHM (50/50 wt/wt) with the acrylic component PMCHM, a copolymer of PMMA and poly(cyclohexyl methacrylate) (80/20 wt/wt), shows only one TI, value, which indicates high miscibility in this blend. A blend of PC/PMMA (50/50 wt/wt) shows two H-1 T1rho values, which are similar to those of the homopolymers PC and PMMA. These results indicate high immiscibility. The "domain size" calculated from NMR results of the miscible blend PC/PMCHM is approximately 40 angstrom. The results of DSC and TEM are similar to the NMR results. However, TEM results show the presence of 3% PC domains in the PC/PMCHM blend, which are not seen by NMR or DSC. Those PC domains are approximately 500 angstrom. A strong intramolecular repulsion in the copolymer PMCHM and specific intermolecular interactions between PC and PMMA may explain the miscibility in the PC/PMCHM system.