The stress distribution on endodontically treated teeth varies with different tapers of root canal preparation and thus the fracture resistance. The objective of this study was to evaluate the stress distribution on endodontically treated teeth between three different tapers of root canal preparation during simulated application of loads on the teeth. In this study, mandibular incisors with straight and mature canals were chosen, cleaning and shaping was done using Hyflex Nickel Titanium (NiTi) rotary instruments. The enlargement was done till 4%, 6% and 8% for design 1, 2, and 3 respectively following which cone beam computed tomography (CBCT) scans were taken. Three finite element analysis models were designed by using three taper designs of root canal superimposed on the same external morphology of a single mandibular incisor. These generated models were assigned to a total force of 70N and 100N which was applied parallel to the long axis of the tooth and at 45 degrees to the long axis of the tooth respectively. The von Misses stresses (VM) throughout the tooth structures were calculated and compared. The results showed that the peak VM stress on all models were at the site of incisal load points. The area of peri-cervical dentin experienced highest VM stresses in all the three designs. This study concluded that highest enamel stress at the incisal load points was seen in all three canal preparation and with increasing taper of the canal, the VM stresses increased.