Abstract: Process for the preparation of polyester-polyurethane flexible foams which do not give rise to the formation of misting, in which at least one polyisocyanate is reacted with at least one polyester pretreated by distillation and water and/or highly volatile organic compounds as blowing agent, characterized in that, in order to obtain the pretreated polyester which is used in the reaction with the polyisocyanate, in a first stage a starting polyester is manufactured which has a hydroxyl value (HV) higher by 4 to 12 mg KOH/g in relation to the HV of the desired pretreated polyester and which has a viscosity, measured at 25.degree. C. with a Brookfield RVT viscometer, lower by 2 to 5 Pa s in relation to that of the desired pretreated polyester and, in a second stage, the said starting polyester is subjected to a distillation for a treatment period of between 2 and 300 seconds, in temperature and pressure conditions making it possible to extract at least 85% of the cyclic diester present in the starting polyester.