(The aim of this study was to evaluate the fracture strength and mode of failure of endodontically treated teeth reconstructed with glass fiber reinforced posts. Twenty maxillary central incisors, extracted for periodontal reasons, were divided in 2 groups: gr. 1 - glass fiber posts, and gr.2 - control (endodontically treated but without posts). All samples were embedded in resin bloks and mounted in stainless steel cylinders for the compressive test. The force was applied on oral surface of the crown, until the failure occurred. The compressive loads at failure were recorded and compared with the statistical method Student t. The mode of failure of the specimens were also evaluated. The statistical analysis of the force values showed no significant difference between the groups. In conclusion, because of their low Young's modulus, the non-metallic posts made of resin composite reinforced with glass fibers have a protective effect on the dental tissues, the recorded mode of failure being very similar with the control group.