Process for preparing hydroxyl group-terminated polyesterols, characterized in that, in a first process step, imide group-containing mono- or polycarboxylic acids are first prepared by reacting (B.1) at least one amino acid having one or more amino groups and one or more acid groups with (B.2) at least one carboxylic anhydride having precisely one anhydride group and no further free acid groups in the presence of at least one diol and/or polyol having a molecular weight of 62 to 1000 g/mol, and, in a second process step, the reaction mixture obtained in the first process step is esterified - without purification, - optionally with addition of further component B.2 and/or further component C and/or further mono- and/or polycarboxylic acids which do not fall under the definition of components and (B.2), under polycondensation conditions, wherein auxiliaries and additives are optionally used in the first process step and/or in the second process step and wherein no further solvent besides component is added in the first process step. in a first process step, imide group-containing mono- or polycarboxylic acids are first prepared by reacting (B.1) at least one amino acid having one or more amino groups and one or more acid groups with (B.2) at least one carboxylic anhydride having precisely one anhydride group and no further free acid groups in the presence of at least one diol and/or polyol having a molecular weight of 62 to 1000 g/mol, and, in a second process step, the reaction mixture obtained in the first process step is esterified - without purification, - optionally with addition of further component B.2 and/or further component C and/or further mono- and/or polycarboxylic acids which do not fall under the definition of components and (B.2), under polycondensation conditions, wherein auxiliaries and additives are optionally used in the first process step and/or in the second process step and (B.1) at least one amino acid having one or more amino groups and one or more acid groups with (B.2) at least one carboxylic anhydride having precisely one anhydride group and no further free acid groups in the presence of at least one diol and/or polyol having a molecular weight of 62 to 1000 g/mol, and, in a second process step, the reaction mixture obtained in the first process step is esterified - without purification, - optionally with addition of further component B.2 and/or further component C and/or further mono- and/or polycarboxylic acids which do not fall under the definition of components and (B.2), under polycondensation conditions, wherein auxiliaries and additives are optionally used in the first process step and/or in the second process step and and, in a second process step, the reaction mixture obtained in the first process step is esterified - without purification, - optionally with addition of further component B.2 and/or further component C and/or further mono- and/or polycarboxylic acids which do not fall under the definition of components and (B.2), under polycondensation conditions, - without purification, - optionally with addition of further component B.2 and/or further component C and/or further mono- and/or polycarboxylic acids which do not fall under the definition of components and (B.2), under polycondensation conditions, wherein auxiliaries and additives are optionally used in the first process step and/or in the second process step and wherein no further solvent besides component is added in the first process step.