A melt blending method was used to prepare acrylonitrile-butadiene-styrene terpolymer and polyethylene terephthalate blends to develop a new blend which can withstand higher temperatures required especially for automotive or home appliance paint curing processes. Blends were characterized by rheological, thermal and mechanical properties. Dimensional stability at 125 degrees C was used to correlate with injection molded part shrinkage. The melt viscosity-composition curves for acrylonitrile-butadiene-styrene/polyethylene terephthalate blends exhibited a trend like the rule of mixtures in which adding acrylonitrile-butadiene-styrene to polyethylene terephthalate improved the processability. Scanning electron microscopy examination revealed different morphologies depending on the composition such as dispersed, co-continuous and phase inverted, which indicated that the binary blends were immiscible and form a two-phase structure. Tensile properties increased with an increase in the polyethylene terephthalate content while the unnotched impact strength reached a maximum at 40 wt.% acrylonitrile-butadiene-styrene content. In differential scanning calorimetry analysis, no partial miscibility was observed from the polyethylene terephthalate phase melting temperature shifts as compared to those of the neat component. Also, acrylonitrile-butadiene-styrene phases acted as nucleating agents due to change in polyethylene terephthalate cold crystallization temperature. In applied post shrinkage measurements by heat aging, we saw that the acrylonitrile-butadiene-styrene dimensional stability was improved with added polyethylene terephthalate.