Abstract: A process is described for preparing polyols in the form of bifunctional aromatic polyester alcohols from PET wastes and wastes from PET production. The process comprises dissolving the PET wastes in diethylene glycol (DEG), with the ratio of wastes to DEG being selected in such a way that the polyester alcohol obtained after the subsequent transesterification has a hydroxyl number (OHN) greater than 700 mg KOH/g, transesterifying the wastes dissolved in DEG and, if required or if desired, freed of solids, using known transesterification catalysts, with the ethylene glycol (EG) liberated in the process being at least partially distilled off, and distilling off free DEG at a temperature of below 140.degree. C. from the transesterification product at equilibrium until a polyester alcohol having an OHN of 260-500 mg KOH/g is obtained.