An iteration method is presented for the accurate calculation of the microwave magnetoconductivity of polar semiconductors. The method is an extension of Rode's iteration method for the evaluation of dc conductivity. The real and imaginary parts of the two perturbation components of the distribution function are obtained at each step of iteration by solving the four simultaneous equations relating the components. The iteration procedure is found to converge within 5-10 steps. The method has been applied to obtain the magnetoconductivity tensor of n-InSb at 10, 35, 85, and 135 GHz for magnetic induction up to 0.1 Wb/m2. All the relevant scattering mechanisms and the effects of band nonparabolicity have been taken into account. The calculated values of conductivity differ significantly from those obtained by applying the Drude theory and do not agree with those deduced from a cavity perturbation experiment.