Disclosed is the use of benzylidene malonates of formula (1), wherein R1 and R2, independently from each other are hydrogen; OH; C1-C12alkyl; C1-C12alkoxy; C1-C12alkylamino; C1-C12dialkylamino; water-solubilizing groups, selected from carboxylate, sulfonates or ammonium radicals; R3 is COOR5; COR5; CONR5R6; CN; or SO2R7, R4 is COOR8; COR9; CONR8R9; CN; or SO2R10; R5, R6, R7, R8, R9 and R10 independently from each other are C1-C18alkyl; unsubstituted or by one or more than one C1-C4alkyl substituted C3-C12-cycloalkyl; unsubstituted or C1-C6alkyl-substituted C6-C20aryl; organosilanyl, or organosiloxanyl; A is —C1-C20alkylene-, —CH2CH(OH)CH2—, —C5-C20cycloalkylene, —C2-C20alkenylene-, —C5-C10arylene-, or —C5-C10arylene-(C1-C10alkylene)- which are unsubstituted or substituted, straight-chain or branched, optionally interrupted by one or more than one heteroatoms selected from —O, —S— or —NH—; for the protection of human and animal hair and skin against UV radiation.