Polymeric compositions with good flame self-extinguishing characteristics,ased on thermoplastic polymers or polymers with elastomeric properties, especially olefinic polymers or copolymers, comprising:a) from 90 to 40 parts by weight of a thermoplastic polymer or a polymer with elastomeric properties;b) from 6 to 33 parts by weight of one or more ammonium or amine phosphates and/or phosphonates;c) from 4 to 27 parts by weight of one or more salts of 2,4,6-triamino-1,3,5-triazine derivatives with cyanuric acid, of general formula (I): ##STR1##