This invention relates to thermoplastic molding compositions with improved flowability based on a thermoplastic polyester and on at least one copolymer composed of at least one olefin with at least one methacrylic ester or acrylic ester of an aliphatic alcohol, the MFI of the copolymer being not less than 50 g/10 min, to a process for preparation of these molding compositions, and also the use of these molding compositions for production of moldings for the electrical, electronics, telecommunications, motor vehicle or computer industry, in sports, in the household, in medicine or for the entertainment industry.