The invention relates to dimeric 2-(2'-hydroxyphenyl)benzotriazoles of the formula I ##STR1## in which p is 0 or 1;A is C.sub.1 -C.sub.12 alkylene;R.sub.1 and R'.sub.1, independently of one another, are hydrogen, halogen, C.sub.1 -C.sub.18 alkyl, C.sub.1 -C.sub.18 alkoxy or --CN;R.sub.2 and R'.sub.2, independently of one another, are hydrogen or C.sub.1 -C.sub.18 alkyl or together are C.sub.2 -C.sub.12 alkylene or C.sub.2 -C.sub.12 hydroxyalkylene; andR.sub.3 and R'.sub.3, independently of one another, are hydrogen, halogen, C.sub.1 -C.sub.18 alkyl or C.sub.1 -C.sub.18 alkoxy.The compounds of formula I are highly suitable for the stabilization of organic material against the harmful effects of heat, oxygen and light, in particular UV radiation.