Abstract In recent years only a few totally new plastics have been developed, since suppliers are finding it quicker and less expensive to tailor existing resins to meet the requirements of a specific application by alloying. The properties of an alloy of polycarbonate and a proprietary copolyester have been fully characterized. Thermal analysis shows that the polymers are miscible in all proportions. Transparency, glass transition temperature, barrier properties, tensile, and flexural properties of the alloy all fall between those of the neat components. Certain synergistic properties were observed upon blending the polycarbonate and polyester. The tendency of the blend not to yellow during γ‐sterilization is remarkably better than can be predicted by an additive relationship. Chemical resistance of the blends behaves in a similar manner. The excellent balance of properties exhibited by the blend such as transparency, impact strength, γ‐radiation resistance, and chemical resistance makes it useful in applications such as medical disposables and filter bowls.