Aim: To investigate the fracture resistance and the mode of failure of custom-made post and cores fabricated with different materials and two post space lengths. Materials and methods:  forty-two extracted maxillary central incisors were chosen, and split into 3 groups randomly (n = 14) according to each material: group 1: Hybrid ceramic (Vita Enamic), group 2: Fiber reinforced composite (Trilor) and group 3: polyetheretherketone (Pekton). All groups were subdivided into two subgroups based on post length (6 mm and 9 mm). All teeth were endodontically treated and the post spaces had been scanned by primescan intraoral scanner. The post-and-cores were designed, manufactured using CAD/CAM and cemented using a self-adhesive resin cement (G-CEM). The fracture resistance was tested in a universal testing machine under controlled load at a crosshead speed of 1mm per minute. The failure mode was tested using optical microscope at a x40 magnification. Statistical analysis was performed using two way ANOVA to detect significance between groups. Results: Two-Way ANOVA showed that both post material and length had a significant effect on fracture resistance (p<0.001). Post material and post lengths interactions had no significant impact on the fracture resistance (p=0.160). Conclusion: Trilor custom-made posts had the highest fracture resistance, with the most unfavorable fracture. Nine mm post length had higher fracture resistance than six mm.