Objective: The aim of this study was to evaluate the effect of different taper on stresses generated within root canals that have varying degree of curvature when subjected to vertical compaction obturation technique. Methods: Thirty extracted teeth were divided into three groups, group1: teeth with straight roots, group 2: teeth with moderate curvature roots, group3: teeth with severe curvature. Each group was divided into two subgroups: A or B according to the preparation taper of root canal either 2% or 6% taper. Molds were constructed to simulate the presence of root within artificial socket, then vertical compaction obturation technique is performed with force equal to 1kg at three levels apical, middle and coronal, then the samples were subjected to loading up to fracture. Results: The result showed that there is no significance difference between the mean of fracture load of straight, moderate and severe curvature among the same group taper but 6% groups showed higher fracture resistance than 2% taper groups. Conclusion: Increasing the canal taper will decrease the internal stresses within the root canal