Polycarbonate was subjected to various combinations of mechanical-thermal histories to investigate such effects on subsequent tensile mechanical properties. This was accomplished by "cold extruding" the material initially; nominal "reductions in area" of 18, 40 and 64% were used. Cold extruded bars were then heat treated at three temperature levels, all being less than T z (150°C) of polycarbonate. As compared with the material that was only cold extruded, it was found that in general, heat treating tends to raise the yield stress while lowering the tensile strength, elastic modulus and stress at fracture. The results suggest that a desired combination of properties may be obtainable by the use of a cold work-heat treating sequence.