The aim of this study was to measure the fracture resistance of endodontically treated maxillary premolars restored with ormocer,hybrid and nanofill composite resins. Fourty sound, caries-free human maxillary premolar teeth were used. The teeth were endodontically treated and MOD cavities prepared. The prepared teeth were randomly divided into four groups of 10 teeth. Each group was restored with four different restorative materials (one ormocer, one nanofill, one hybrid and one high copper amalgam). Copper rings were filled with self-curing polymethylmetacrylate resin and the teeth were placed into resin up to the level of the cementoenamel junction. The copper rings with the teeth were placed into a Universal Testing Machine and the buccal walls were subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the various groups compared. Statistical analysis was performed by using one way analysis of variance(ANOVA).There was no statistically significant difference between the groups. There was no difference in the fracture resistance of endodontically treated teeth following restoration with amalgam and composite restorative materials. Within the limits of this study we can suggest that resins used in this study are good alternative materials to amalgam.