The report deals with a retrospective comparison of the effectiveness of standard and large-fractionated preoperative radiation therapy of breast cancer patients (each group included 85 females). As a result of distant irradiation with daily single doses of 4 Gy (total dose--20 Gy), preoperative admission period was reduced 5--7 times, as compared with standard single doses of 2 Gy and total dosage of 40--45 Gy. Large--fractionated radiation therapy results in a relatively low incidence of general and local reactions, does not interfere with surgery and is followed by postoperative complications in fewer cases. The distant metastasis frequency was significantly lower (51 +/- 5 and 32 +/- 5%, respectively), while the 5-year survival rate--higher (45 +/- 5 and 65 +/-5%, respectively) in application of large--fractionated radiation therapy. The said advantages were particularly apparent in cases of local operable tumors (stage III); in such patients, the 5-year survival rate rose from 40 +/- 7 to 64 +/- 6% (p greater than 0.05).