The blend compatibility of methyl methacrylate (MMA)-benzyl methacrylate (BzMA) copolymers with different monomer compositions has been studied to investigate their feasibility as plastic optical fibers. Copolymers with variable comonomer composition were first synthesized, and the blend compatibility between them was investigated by solution blending and melt blending. The results of H-1 NMR, ellipsometry, and differential scanning calorimetry indicate that the copolymers synthesized in this study are random copolymers, with their refractive index and the glass transition temperature varying linearly with their monomer content. While the solution-blended samples indicated immiscibility between copolymers with large differences in their monomer composition, melt-blended samples indicated miscibility showing single glass transition temperature and homogeneity in scanning electron micrographs. The difference between the results of solution blends and melt blends may be attributed to the slow kinetics of phase separation and the intensive shear energy input during melt blending. These results suggest that MMA-BzMA random copolymers are appropriate materials applicable to the coextrusion method of Park and Walker (U.S. Patent 89 929 161, 1997) for the fabrication of graded-index plastic optical fibers.