Abstract: A polylactide-based polymer or copolymer (PLA) compositions with improved flame retardancy properties as obtained by conventional melt-blending of PLA polyester matrix (1) with both calcium sulfate (2) and organo-modified layered silicates (OMLS) (3). Combination of CaSO4 and OMLS exhibits synergistic effects on PLA flame retardancy by both significantly increasing the time to ignition and decreasing the heat release rate per unit area, and promoting non-dripping properties. Moreover, all other properties of PLA remain almost unchanged or are improved as regards to pristine PLA, especially thermal and mechanical properties.