Intraoperative Radiation therapy (IORT) is a cancer treatment modality in which resectable masses or organs are removed surgically and residual cancer calls are sterilized by irradiation with a single massive dose during while patient is still anesthetized. Because it is possible that the turner mass can be visualized directly at the time of surgical exploration, tumor volume can be determined more precisely and at the same tin e sensitive adjacent structures can be pulled aside from the irradiation. With these theoretical advantages as compare to conventional external irradiation, IORT can improve the therapeutic ratio of tumor control to normal tissue injury. Yonsei cancer center initiated a pilot study of multidisciplinary IORT program in february of 1986 for the fist attempt in Korea. IORT Was performed in 7 patients with stomach cancer by using existing NELAC-1018 Linear Accelerator treatment room as a surgical suite. IOTR team included department of surgery, Department of Anethesiology, Department of Clinical pathology, operating room nursing personal and Department of radiation oncology.