The present invention relates to a cationic poly(ether-urethane) constructed from a) at least one polyetherol, as component A; b) at least one tertiary amine-containing or ammonium-containing diol, as component B; c) at least one diisocyanate as component C; d) optionally at least one short-stopper, as component D; where the cationic poly(ether-urethane) has an amine number of from 5 to 40. Furthermore, the present invention relates to a process for the preparation of the cationic poly(ether-urethanes), according to the invention, to compositions comprising the cationic poly(ether-urethanes) according to the invention and also at least one anionic surfactant, to a method of foam regulation, in particular for suppressing foam or for defoaming using at least one cationic poly(ether-urethane) according to the invention, to the use of the cationic poly(ether-urethane) according to the invention for foam regulation, in particular as foam suppressor or defoamer.