Validation of the oncological safety of nipple-sparing subcutaneous mastectomy and immediate reconstruction with implants (NSM) and of the outcome in patients with locoregional recurrences (LRRs) after this procedure. Two-hundred and sixteen patients, mean age of 52.8 (29-81) years with primary unilateral breast cancer, not suitable for partial mastectomy because of large (>3cm) or multifocal carcinoma, underwent NSM, a single procedure lasting about 1h 30min, between December 1988 and September 1994. Lymph node metastases were found in 40.3% of the patients, and 47 patients received radiotherapy (RT) postoperatively. All patients were monitored for at least 11.6 years or as long as they lived. Median follow-up was 13 years. The end-points were locoregional recurrence (LRR) or distant metastases (DM) as first events, disease-free survival (DFS) and overall survival (OS). Specificity at frozen section from sub-areolar tissues was 98.5%. LRR occurred in 52 patients and DM in 44 patients. DFS was 51.3% and OS was 76.4%. The frequency of LRR was 8.5% among irradiated and 28.4% among non-irradiated patients (p=0.025). These results compare well with results after conventional mastectomy in other trials. All patients were monitored for at least 6 years after the occurrence of LRR, finding 5 years freedom from further LRR or DM of 60% and OS of 82%. NSM is an oncologically safe procedure and could be offered to most patients with breast cancer unsuitable for sector resection only. RT effectively lowers the frequency of LRR. The occurrence of LRR after this operation does not significantly affect OS.