Registration is a process to align different acquired images of the same subject. A major problem in this field is to register images captured by different imaging systems. These images have different gray values so simple methods like correlation are not applicable. In this paper automated registration of CT and MR head images is studied. It is assumed that images are only of relative translation and rotation. The proposed method includes two stages. First, feature extraction of CT and MR images, (should be extractable and constant in both imaging systems). Second, feature alignment which is moment-based. The results confirm the accuracy and robustness of the proposed method.