It is more realistic to include the effect of adjacent teeth stiffness while evaluating the root stresses of a gear which is a rotationally periodic structure. This requires very large core and computational time. In the present analysis an attempt has been made to compare the root stresses with and without considering the effects of adjacent gear teeth stiffnesses using the concept of cyclic symmetry. Further, an attempt has been made to study the performance of a composite spur gear using the above approach. It is found that the root structure predicted by the method of cyclic symmetry is less for both isotropic and orthotropic spur gears. © 1993.