The prognosis of root-filled teeth depends not only on the success of the endodontic treatment, but also on the success of the final restoration. Fractures of restored endodontically treated teeth are common occurrence in clinical practice. Indiscriminate use of chemical irrigants and medicaments can impair the physical, chemical and mechanical properties of dentin. Aggressive instrumentation and/or removal of dentin will also compromise the mechanical integrity of the remaining tooth structure. Unfortunately, currently there is no treatment approach that can restore the mechanical integrity of endodontically treated teeth. This lecture will address the risk factors for fracture predilection and the clinical steps to possibly improve the mechanical integrity of endodontically treated teeth.