Abstract: Stabilizer system consisting of(a) at least one sterically hindered cyclic amine of the formula I ##STR1## in which q is 1 or 2, X represents an organic grouping which complements the nitrogen-containing ring to give a 5-membered, 6-membered or 7-membered ring, R.sub.1 and R.sub.2 represent methyl or together represent --(CH.sub.2).sub.5 --, R.sub.3 represents methyl, R.sub.4 represents alkyl with 1-5 carbon atoms or together with R.sub.3 represents the radicals --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.5 -- ##STR2## and, if q is 1, Y denotes hydrogen, --0.sup.., hydroxyl, alkyl, substituted akyl, alkenyl, alkinyl, aralkyl, substituted aralkyl or acyl or, if q is 2, Y denotes alkylene, alkenylene, alkinylene, cycloalkylene or aralkylene, and(b) at least one co-stabilizer for stabilizing plastics.