Thermoplastic molding compositions comprise A) from 30 to 96% by weight of a polyester B) from 1 to 30% by weight of melamine cyanurate C) from 1 to 30% by weight of at least one phosphorus-containing flame retardant D) from 0.01 to 5% by weight of at least one ester or amide derived from a saturated or unsaturated aliphatic carboxylic acid having from 10 to 40 carbon atoms and a saturated aliphatic alcohol or &mine having from 2 to 40 carbon atoms E) from 0 to 60% by weight of other additives and processing aids where the total of the percentages by weight of components A) to E) is 100%.