After conservative surgery 491 women with unilateral, invasive breast cancer were irradiated with a median dose of 50 Gy (ICRU-point) for the whole breast and an additional boost of 20 Gy respectively. The mean (median) follow-up was 69.7 (60) months with a range from 24 to 221 months. The surgical interventions were called tumorectomy in 16.1%, lumpectomy in 63.5% and quadrantectomy in 20.4%. The tumour size was classified in 73.5% (361/491) as pT1 and in 23.5% (117/491) as pT2. 2.7% were > pT2-tumours. A dissection of the axilla (473/491) recovered at the median 16 lymph nodes (0 to 48), of whom on an average 3.7 (1 to 46) contained metastases. According to Kaplan-Meier the five and ten year survival rates yielded the following respective end-points: local relapse free 94.5% and 89.2%, free of distant metastases 84.5% and 75.6%, disease free 80.7% and 69.4%, cause specific 90.3% and 79.1% and overall survival 89.5% and 76.4%. In patients with positive margins local relapses were seen in 14.6% and distant metastases in 26.8%, versus 5.7% and 16.1% respectively for the whole cohort. If even a re-excision couldn't get clear margins, 27.3% of these patients developed a local failure and 45.5% distant metastases. In contrast, the corresponding data for a re-excision specimen with residual tumour but negative margins were 9.9% and 12.3%. Possibly, the ability to achieve clear margins is not only a local problem, but an expression of the tumour biology. Another risk factor seems to be tumour necrosis: 16.2% local and 35% distant relapses occurred compared to 4.8% and 14.5% in patients without this histological feature. All acquired data are listed in Table 2. Their statistical relevance according to the log rank test is given in Table 3. No significance was seen for adjuvant systemic treatments. Both groups of patients were, however, not very well balanced with respect to conventional risk factors.