Abstract Aims: The aim of this study is to determine and compare the fracture resistance of endodontically treated teeth restored with different fibre reinforced post system. Materials and Method: A total number of 45 non-carious, single rooted human mandibular premolar teeth were selected, which were extracted for orthodontic and periodontal purpose only. After decoronation, single cone obturation and post space preparation Teeth were randomly allocated into 3 groups. Group A: Zirconia modified cylindrical fibre post (n=15); Group B: Tapered Glass fibre post (n=15); Group C: Double tapered fibre post (n=15). The different fibre post systems were cemented with paracore dual cured resin cement. Each specimen was mounted in acrylic block. Compressive loading was applied using Universal testing machine at a speed of 1mm/min in Apical direction till fracture. The fracture load was measured in newtons and converted to megapascals. Results: Statical analysis was done. Fracture resistance of human mandibular premolar teeth restored with zirconia modified cylindrical post system (Dentsply Easypost) has highest fracture resistance among the groups tested and statistically significant than the other groups. teeth restored with double tapered glass fibre post (Angelus Exacto) has lowest fracture resistance among the groups tested. Conclusion: Within the parameters and limitations of this study it may be concluded that Fracture resistance of human mandibular premolar teeth restored with zirconia modified cylindrical post system (Dentsply Easypost) has highest fracture resistance among the groups tested.