Virgin and organoclay modified polycarbonate (PC)/ poly(methyl methacrylate) (PMMA) (30/70 w/w) blends were prepared by melt-mixing of PC, PMMA, and organically modified montmorillonite (OMMT). The morphology of OMMT modified PC/PMMA blend with two different weight percents of OMMT was studied using scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The size of the phase-separated domains decreased dramatically with increasing the content of OMMT. XRD patterns and TEM observations revealed that silicate layers were intercalated and nicely dispersed in the blend matrix. Differential scanning calorimetry analyses showed efficient mixing of two immiscible polymers in the presence of OMMT. The blend nanocomposites showed greatly improved mechanical properties when compared with the same blend sample without OMMT. Finally, the opaque immiscible PC/PMMA blend became translucent after modification with OMMT addition.