© 2016 Wiley Periodicals, Inc.Objective: To compare the fracture resistance of endodontically treated maxillary premolars with one remaining cavity wall restored either with short fiber-reinforced composite or polyethylene woven fiber-reinforced composite. Materials and Methods: Forty-eight maxillary premolars were endodontically treated and randomly assigned to four groups (n = 12). Palatal cusp was removed, buccal wall was remained. In groups 1 to 3, standardized cavities were prepared in the palatal canal entrances. In group 1, short fiber-reinforced composite was used for restoration both of deep cavity and coronal part. In group 2, short fiber-reinforced composite was placed inside the deep cavity and core part of the restoration. Coronal restoration was restored by using conventional filler composite. In group 3, both deep cavities and coronal parts were built up by using conventional filler composite. In group 4, post space was prepared in the palatal canal. Polyethylene woven fiber-reinforced composite post then was placed into post space and the coronal part was restored by using conventional filler composite. Specimens were placed into a universal testing machine. The fracture loads were recorded and analyzed statistically using one-way ANOVA (α = 0.05). Fracture patterns were analyzed by using Chi-square test (α = 0.05). Results: No statistically significant difference was found in fracture strength (p > 0.05). Group 1 exhibited the highest and group 4 exhibited the lowest incidence of restorable fracture (p < 0.05). Conclusions: The restoration of severely weakened premolar teeth with the use of short fiber-reinforced composite might have advantages over conventional filler composite or polyethylene woven fiber-reinforced composite techniques. Clinical Significance: The results of this in vitro study will be helpful to understand reinforced composite materials for restoring endodontically treated maxillary premolars. (J Esthet Restor Dent 28:412–418, 2016).