The compatibilizing effect of poly(hydroxy ether of Bisphenol A) (Phenoxy) on the immiscible poly(butylene terephthalate) (PBT)/poly(methyl methacrylate) (PMMA) blends was examined by differential scanning calorimetry and scanning electron miscoscopy. It was found that the Phenoxy, which was miscible with each of the other blend components, solubilized the two immiscible polymers at its loading levels greater than 50 wt%. When a small amount of Phenoxy was added to the immiscible blends, the morphology changed into more regular and finer dispersion. The tensile properties are increased as the content of Phenoxy increases, although the improvement is limited. From the morphology and mechanical properties, it is concluded that Phenoxy plays an appropriate role in compatibilizing the immiscible blends of PBT and PMMA.