Poly(oxyalkylene)urethane surfactants of the formula (I) R2—X—OCHN—[R1—NHCO—O—[(CH2)q—O]x—CONH—]nR1—NHCO—X—R2  (I) in which R1: an alkylene radical, a cycloalkylene radical or an arylene radical; X: —O— or —NH—; R2: a linear or branched (C1-C4)-alkyl radical, monosubstituted by a group selected from: sulfo, carboxyl and [N,N-di-(C1-C4)-alkyl]amino, or disubstituted by: carboxyl; carboxyl and hydroxyl; carboxyl and mercapto; or, if X=—O—, R2 may also be defined as [R3—O—CONH—R1—NHCO—O—]mR4 in which R3: a linear or branched (C1-C4)-alkylene radical, monosubstituted by COOH, especially a —CH2—[C(COOH)(CH3)]—CH2— radical, R1 is as defined above, and R4: C2-C22-alkyl or a —CH2—[C(COOH)(CH3)]—CH2—OH radical, and m=an integer from 1 to 10; n=an integer from 1 to 7; q=an integer from 3 to 5; and x=an integer from 10 to 70; and the water-soluble or water-dispersible salts thereof are described as a solubilizer and stabilizer in active ingredient formulations.