More recently, there is an increasing interest in finding materials that would compete in the market with its good properties, biodegradation and renewable energy production. Biopolymers are increasingly used today to reduce the adverse environmental impact of polymers. One of the wide known biodegradable polymers is polylactide. By adding synthetic or natural inorganic materials to the polymer matrix properties of the polymeric materials could be improved and the price of the material could be lowered. In this study the effect of filler addition (A200, R711, R805 and R816) in different quantities in polylactide was investigated. Samples were prepared by melt mixing in a Brabender plasticoder. Interactions on the filler/matrix interphase were determinated with the contact angle measurements. Mechanical properties and mechanism of faliure were investigated with the tensile test on the universal mechanical testing machine. Thermal properties were investigated with differential scanning analysis and thermal stability with termogravimetric analysis. The results of the contact angle measurement with water show poor hydrophilicity of the polylactide surface. Fillers A200 and R816 show hydrophilic and R711 and R816 hydrophobic nature of the filler surface. From the results of the DSC measurements it is visible that addition of the filler has no influence on the PLA glass transition temperature. Addition of the filler increases the degree of crystallinity and shows nucleation effect on the PLA crystallization. In the PLA composites where silica surface is modified with metacryl silane R711 and octylsilane R805 addition of the filler decreases crystallization rate of PLA. Thermal stability is increased with the addition of silica filler in PLA matrix. The results of the mechanical properties showed that addition of silica fillers in the pure PLA matrix did not have any significant effect on the elongation. All curves show maximal elongation at break of 4%, and the best mechanical properties have PLA / R711 composites.