Aim of this study was to evaluate the fracture resistance of three different post materials two different post lengths. Materials: polyethylene fiber posts, Ever stick fiber posts, Rely-x fiber posts. Methods: thirty sound mandibular premolars were collected. Each sample had their crown sectioned 2 mm coronal to the proximal Cement- Enamel junction, then were endodontically treated using rotary system (Bio-Race). Acrylic resin blocks were constructed for each sample using Teflon mold and centralizing device. Periodontal substitution was done by using regular body impression material. Ferrule was prepared using a milling machine.Samples were divided into three main groups according to the post type A, B,C. Each main group was subdivided into 2 subgroups according to post length. Subgroups: a1,b1,c1 at 6mm and subgroups:a2,b2,c2 at 8mm. Core build up was done using core build up material in conjunction with core former. Each sample received static axial load at universal testing machine till failure; data were collected and statistically analyzed. Results: the post type and material had a stalactitically significant effect on mean fracture Resistance. Post length had no statistically significant effect on mean fracture resistance.Rely-X post showed the highest mean fracture resistance value followed by Everstick and Ribbond postsrespectively. Regarding the mode of failure Rely -X post showed the worst mode of failure followed byEverstick and Ribbond groups respectively. Conclusion: newly introduced posts Everstick and Ribbond have a favorable prognosis in the fracture mode . Post lengths did not influence the fracture resistance of endodontically treated teeth.