This communication describes the compatibilization efficiency of organically modified montmorillonite (OMMT) in immiscible polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends for the first time. The size of the dispersed PC particles was reduced significantly upon the addition of OMMT (6 wt.-%) to the blend. The compatibilization effect of the OMMT was also assessed by differential scanning calorimetry, mechanical properties and thermal stability analysis of the modified blend.