Novel furancarboxylic acid derivatives of the general formula ##STR1## where R.sup.1, R.sup.2 and R.sup.3 independently of one another are each hydrogen, C.sub.1 -C.sub.8 -alkyl, cyclohexyl or phenyl, but not more than two of these radicals are simultaneously hydrogen, and R.sup.4 is a radical of the formula --NR.sup.5 R.sup.6, ##STR2## or OR.sup.6, where A is a bridge member, R.sup.5 is hydrogen, C.sub.2 -C.sub.6 -alkenyl, C.sub.5 -C.sub.7 -cycloalkyl or C.sub.1 -C.sub.12 -alkyl which may or may not be interrupted by 1, 2 or 3 oxygen atoms, and R.sup.6 is a radical of the formula ##STR3## where R.sup.7, R.sup.8, R.sup.9 and R.sup.10 are each C.sub.1 -C.sub.4 -alkyl, or R.sup.7 and R.sup.8 or R.sup.9 and R.sup.10 together form a tetramethylene or pentamethylene bridge, and R.sup.11 is hydrogen, C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.8 -alkenyl, C.sub.2 -C.sub.4 -hydroxyalkyl or aralkyl, and their salts are useful as light stabilizers for organic polymers, in particular olefin polymers.