Theoretical, experimental and clinical rationale is discussed for selection of targets and main parameters of intraoperative radiotherapy for gastric cancer. Topometric and dosage research has been carried out. Original technological equipment has been developed for safe treatment using the domestic accelerator Mikrotron-M. Procedures for continuous relay pre- and intraoperative radiotherapy of gastric tumors in conjunction with radical surgery have been devised and adapted to operation of a specialized clinical facility.