[en] Purpose: Analysis of the indications and cosmetic results in patients, which were conduct postoperative radiotherapy with simultaneous integrated boost on tumor bed after organ-preserving surgery. Material and method: For the period of from December 2016 until January 2019, 26 patients with breast cancer conducted postoperative radiotherapy with a simultaneous integrated ) boost. Patients age were from 29 to 78 years: mean age 51 ). The follow-up period is 3 to 26 11 months. (mean 9 months). The characteristics of patients according to T and N were: pT1 c - 11 (42%) patients, with pT2 - 15 (58%), of which pN0 - 20 (76%) patients and pN + - 6 (34%). The histology type of the tumor was invasive ductal carcinoma in all patients. According to the grade of malignancy with G2 were 11 (42%) patients, with G3 - 15 (58%) patients. In 2 (7.6%) of all patients histologically was found lymphovascular invasion (LVSI), in 2 (7.6%) - perineural invasion (PNI) and 3 (11.5%) were with DCIS. A total dose of 50 Gy was realized at a daily dose of 2 Gy for the breast gland and an overdose for the tumor bed by a simultaneous integrated boost of 2.4 Gy to a total dose of 60 Gy. Results: All analyzed patients are alive, with no evidence of local recurrence and distant metastases. No late radiation skin reactions have been detected in the irradiated area. Conclusion: Postoperative radiotherapy with a simultaneous integrated boost in breast cancer ensures local control of the disease, without increasing late radiation responses and with the same prolonged treatment time. Key words: breast cancer, radiotherapy, simultaneous integrated boost.