Transparent polycarbonate PBT blends

A method for increasing the TLT value of a thermoplastic molding composition which contains 1 to 30 % relative to its weight of polybutylene terephthalate the balance being either one of (i) a first aromatic polycarbonate resin or (ii) a second aromatic polycarbonate resin, comprising substituting at least some of said balance by the complementary component selected from said (ii) and said (i), to form a blend containing polybutylene terephthalate, (i) and (ii), wherein each of said (i) and said (ii) is present in the composition having increased TLT value in an amount of 20 to 60% by weight, said second aromatic polycarbonate resin being different from said first aromatic polycarbonate resin in that it contains about 10 to 100% structural units derived from a dihydroxy compound having a bridging unit corresponding to ##STR7## wherein R.sup.3 and R.sup.4 independently one of the other represents a hydrogen atom or a C.sub.1-6 alkyl and X denotes carbon, with the proviso that R.sup.3 and R.sup.4 both represent an alkyl radical on at least one of the X carbon atoms, and where m is an integer of 4 to 10, said TLT being determined in accordance with ASTM D-1003 using specimens 0.100" in thickness.