The tolerance of tissues to radiation is an inverse function of the volume irradiated. Portals should be no larger than necessary to cover the tumor-bearing areas. The widespread practice of using four or even six 15 × l0-cm. portals in the external irradiation of carcinoma of the cervix with medium voltage (200 to 400 kv) irradiates a large volume of tissue unnecessarily. Delivering high doses to such large areas increases the incidence of severe complications, and eventually lowers the cure rate (2,7,12). The availability of multimillion-volt therapy renders integrated planning and accurate aiming to secure minimal but adequate coverage of the tumor-bearing areas most imperative. Arrangement of the pelvic portals depends upon the purpose to be achieved: whether treatment of the primary tumor and its extensions or treatment of the lateral aspects of the parametria and lymph nodes only, as a supplement to local irradiation by intracavitary radium (5). For the former, the whole pelvis is included; for the latter, only a slab of tissue covering the lateral aspects of the parametria and the pel vic wall. If mediumvoltage therapy is used as a supplement to intracavitary radium therapy, the treatment should be limited to the pelvic wall nodes. If larger volumes are irradiated, to include the common iliac nodes, the tumor dose has to be lowered below effective levels. Supervoltage therapy, with or without rotation and megavoltage therapy (betatrons and linear accelerators), makes it possible to deliver very high doses to larger volumes of tissue, with satisfactory tolerance during treatment. It brings about the possibility of a radical departure in the planning of treatment of squamous-cell carcinomas of the uterine cervix. The classical handling of the primary lesion with well performed intracavitary radium therapy or transvaginal therapy with moderate supplementary irradiation to the lateral aspects of the parametria and pelvic wall nodes yields high cure rates, with a low incidence of complication, in Stage I and early Stage II carcinoma. The management of late Stage II, Stage III, and Stage IV lesions, and some clinical varieties of Stage I, is much less satisfactory, failure being attributable in many instances to lack of control of the disease within the pelvis or in the nodes along the common iliac vessels. It is in this latter group that the practice of primary radium therapy supplemented by external irradiation can be reversed by irradiating the whole pelvis and part of the common iliac nodes with high doses and supplementing the treatment of the primary by much reduced intracavitary radium or transvaginal therapy. In the M. D. Anderson Hospital, the practice of taking films with the therapy unit in actual treatment position in order to check the position of the pelvic portals, has taught us that individual variations in the tilt of the pelvis preclude the use of the same surface landmarks, even bony ones, on every patient.