This paper presents a combination of the conjugate gradient method and the fast Fourier transform technique. With this combination, the computational time required to solve large scatterer problems is much less than the time required by the ordinary conjugate gradient method and the method of moments. Since the spatial derivatives are placed with simple multiplications in the transformed domain some of the computational difficulties present in the ordinary conjugate gradient method and the method of moments do not exist. Therefore, electrically small structures can also be handled more easily. Since the method is iterative, it is possible to know the accuracy in a problem solution.