The present invention relates to a process for preparing amino-functional polyurethane prepolymers by a) preparing an NCO-functional polyurethane prepolymer by reacting an excess of one or more di- and/or polyisocyanates with at least one isocyanate-reactive compound having a functionality of at least 1.5, b) reacting the free NCO groups of the resulting polyurethane prepolymer with at least one compound containing one or more silanol groups to obtain the corresponding silylurethanes, and then c) converting the silylurethanes to amino-functional polyurethane prepolymers by hydrolysis and/or alcoholysis with decarboxylation. The present invention also relates coatings, adhesives, sealants, casting compounds or moldings obtained from these amino-functional polyurethene prepolymers. Finally, the present invention relates to reactive systems containing the amino-functional polyurethane prepolymers, compounds containing on average more than one oxirane group per molecule, and optionally organic amines and additives.