The compatibility behaviour of melt-mixed blends of an amorphous copolyester (poly(ethylene-co-cyclohexane 1,4-dimethanol terephthalate), PETG) with poly(ethylene terephthalate) (PET), was investigated over the complete composition range. The techniques applied were dynamic mechanical analysis, tensile resting and differential scanning calorimetry. The effect of thermal history was also examined. In quenched blends tensile properties were good in all compositions. Suitable treatment of thermal data allowed the determination of the polymer-polymer interaction parameter chi(12) whose value supports the view that the blend is miscible at increased PETG levels.