The remotely controlled after loading apparatus, Toshiba RAL 303, was installed in Yonsei Cancer Center in 1979. The intracavitary irradiation method of high dose rate is very different from low dose rate such as radium 226. The irradiation of high dose rate is more effective for relative biological effects but it need precisely to dosimetry and dose distribution in tissue. We described the properties of apparatus, protective room and its advantages and studied the arrangement of sources and dose distribution to be directly applied to Korean patients. The dose distribution varied considerably with arrangement of radiation sources. degree of vaginal extension, length and angulation of uterine cavity and mode of tumor growth to obtain some indices for the optimum arrangement of radiation sources and dose fractions, statistical evaluation was made on 82 patients who had erceived the intracavitary radiotheraphy. Using the statistical evaluation , radiobiological effects, computer program and simulating method, we established the theraphy process and treatment planning of high dose rate intracavitary irradiation and provided the charts and diagram of the dose distribution according to arrangement of sources.