Bond strengths between various materials for endodontic post-core buildups are unknown. The study determined the diametral tensile strength of three esthetic post systems bonded directly or indirectly to four core materials, and subsequent scanning electron microscopy was performed on the fractures. Cylindric core buildup was made around the parallel-sided section of the posts using a custommade jig. Strength was tested after 14 days. A significant difference was found between the control group and the other groups ( P = .0001). SEM observations were in agreement with the results. Apart from the control group, the results suggested that directly and indirectly performed post-core buildups have similar diametral tensile strength values.