Polyester-carbonate resin blends

A thermoplastic composition comprising in admixture

• (a) an aromatic polyester-carbonate and
• (b) an aromatic polyester-carbonate heat distortion improving effective amount of at least one polymer selected from the group consisting of
• (i) aromatic polyamide of the formula ##STR8## wherein R.sup.3 and R.sup.5 are independently selected from halogen, alkyl of one to twelve carbon atoms, and substituted alkyl wherein the substituent is halogen or OR.sup.7 wherein R.sup.7 is an alkyl of one to ten carbon atoms;
• R.sup.4 and R.sup.6 are independently selected from alkyl of one to twelve carbon atoms, hydrogen, aryl of six to eighteen carbon atoms, aralkyl of seven to eighteen carbon atoms, and alkaryl of seven to eighteen carbon atoms;
• a is from 10 to abut 500;
• b and c are independently selected from an integer of 0 to 4.
• (ii) aromatic polyamideimides
• (iii) polyimides.