The movement of isocenter and dose distributions for the partial rotation of cobalt-60 teletherapy were studied for further effective and accurate treatment planning. The isodose curves for various field size and angulation of the partial rotation therapy were constructed by gammagrams taken under the identical points of rotation center and the center of 25 cm diameter circular phantom. the isodose distributions for partial rotation were varied according to field size and rotating angulation, shown in Fig. 3,4. The maximum siocenter from the rotation center was displaced and maximum doses for rotation center doses were varied by angulation of rotation and field size, shown in Table I.II.