The decreased strength seen in endodontically treated teeth is primarily because of the loss of coronal tooth structure; it is not a direct result of the endodontic treatment. Endodontic access in the pulp chamber destroys the structural integrity provided by the coronal dentin of the pulpal roof & allows greater flexing of the tooth under function. In cases with significantly reduced remaining tooth structure, normal functional forces may fracture undermined cusps or fracture the tooth in the area of the smallest circumference, frequently at the cemento-enamel junction. The decreased volume of tooth structure from the combined effect of prior dental procedure creates a significant potential for fracture of the endodontically treated tooth. To prevent this kind of fracture the tooth needs to be reinforced by with the help of post and core. This procedure requires the dentist to follow certain rules during the placement of the same so as to receive the best, long-standing and desired results. The following book intends discuss the various types of posts and core, their requirements and method for regaining the lost strength of endodontically treated teeth.