Abstract: Shaped or unshaped synthetic resins having about 0.01-5% by weight of stabilizers where the stabilizers are bisamides of quadratic acids having the general formulas I and/or II as follows: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4, are identical or different, and represent(A) hydrogen, unsubstituted or substituted alkyl or alkenyl residues of 1-22 carbon atoms, one or more of which can also be substituted by hetero atoms;(B) unsubstituted or substituted cycloalkyl or cycloalkylalkylene residues;(C) unsubstituted or substituted aryl and arylalkylene residues;(D) 3- to 8-membered, unsubstituted or substituted rings which contain one or more hetero atoms and which can optionally be connected to the nitrogen atoms of Formulae I and II by way of alkylene groups;(E) furthermore the groups --NR.sub.1 R.sub.2 and/or --NR.sub.3 R.sub.4 represent 3- to 8-membered, unsubstituted or substituted rings which optionally contain additional hetero atoms; and(F) respectively R.sub.1 and R.sub.3 or R.sub.2 and R.