Conservative surgery (sectoral or segmental + axillary dissection) was performed in 278 patients with breast cancer (T1-2N0M0) at the Institute Clinic in 1990-1995. Following thorough morphological examination. 148 patients (53.2%) were selected to form a clinical study group for an investigation of the role of postoperative radiotherapy in the conservative treatment of breast cancer. Two groups-irradiation of the remaining breast tissue and controls-were formed on the basis of randomized data. Follow-up continued 3-60 months (average duration-37.7 months). Local recurrence was detected in 3 out of 73 (4.2%) patients of group I. A similar relapse was detected in 6 out of 75 (8.0%) patients of group II. No significant difference in total survival rates in the two groups was observed (97.3 and 96.0%; p > 0.05).