Disclosed are-(2′-Hydroxy-4′-aminophenyl)benzotriazole derivatives of formula wherein R1 and R4 independently of each other are hydrogen; C1-C28alkyl; C1-C28alkoxy; C2-C28alkenyl; C2-C28alkinyl; C3-C12cycloalkyl; C3-C12cycloalkenyl; C7-C28aralkyl; C1-C20heteroalkyl; C3-C12cycloheteroalkyl; or C5-C16 heteroaralkyl; and wherein C1-C28alkyl, C1-C28alkoxy, C2-C28alkenyl and C2-C28alkinyl are unsubstituted or may be substituted by at least one C1-C5alkyl, C1-C5alkoxy or hydroxy; R2 and R3 independently of each other are hydrogen; C1-C28alkyl; C2-C28 alkenyl; C2-C22alkinyl; C3-C12cycloalkyl; C3-C12cycloalkenyl; C7-C28 aralkyl; C1-C20 heteroalkyl; C3-C12cycloheteroalkyl; C5-C16heteroaralkyl; and wherein C1-C28alkyl, C1-C28alkoxy, C2-C28alkenyl and C2-C28alkinyl are unsubstituted or may be substituted by at least one C1-C5alkyl, C1-C5alkoxy or hydroxy; or CO—R5; or R2 and R3 together with the linking nitrogen form a 5- to 7-membered, monocyclic, carbocyclic or heterocyclic ring; R5 is C1-C28alkyl; C2-C28alkenyl; C2-C28alkinyl; C3-C12cycloalkyl; C3-C12cycloalkenyl; C7-C20aralkyl; C1-C20 heteroalkyl; C3-C12 cycloheteroalkyl; C1-C5alkoxycarbonyl-C1-C5alkyl; or C5-C16heteroaralkyl; for protecting human and animal hair and skin from harmful effects of UV radiation.