Purpose: This study was undertaken to characterize the fracture resistance and mode of fracture of endodontically treated incisors restored with cast post-and-core, prefabricated stainless steel post, or carbon fiber–reinforced composite post systems. Materials and Methods: Ten endodontically treated teeth restored with each technique were subjected to a compressive load delivered at a 130-degree angle to the long axis until the first sign of failure was noted. The fracture load and the mode of fracture were recorded. Results: The failure loads registered in the three groups were not significantly different. Between 70% and 80% of teeth from any of the three groups displayed fractures that were located above the simulated bone level. Conclusion: The use of carbon fiber–reinforced composite posts did not change the fracture resistance or the failure mode of endodontically treated central incisors compared to the use of metallic posts. Int J Prosthodont 2001;14:141–145.