The aim of this study was to identify the prognostic factors associated with the risk of loco-regional recurrence (LRR) of women undergoing mastectomy and complete axillary dissection without radiotherapy. We analyzed data from 650 women operated between 1997 and 2001 in a single institution. Median follow-up was 10 years. Overall survival was 89.8 % at 5 years and 76.6 % at 10 years. The 10-year cumulative incidence of LRRs was 10.0 % (5.0, 10.5, 15.8, and 18.5 % in patients with 0, 1-3, 4-9, and ≥10 positive lymph nodes (LNs), respectively). Sixty-two (9.5 %) LRRs were observed, 5 (0.8 %) of which occurred in the axillary LNs. Supraclavicular LNs recurrences (n = 16, 2.5 %) occurred more frequently in patients with four or more positive LNs, Ki-67 ≥ 20 % or extensive peritumoral vascular invasion (PVI). At multivariable analysis, nodal status was the only prognostic factor for local events, while nodal status, Ki-67 and PVI were significant prognostic factors for recurrences in the regional LNs. Moreover, within each category of positive LNs, high values of Ki-67 and extensive PVI were associated with the highest risk of LRR while low values of Ki-67 and absence of extensive PVI were associated with the lowest risk of LRR. Women with node-negative tumors have the lowest risk of LRR and represent the group of patients that might benefit the least from radiotherapy. PVI and Ki-67 might help tailoring PMRT indications among patients with positive LNs. Finally, the very low incidence of recurrences in the axillary LNs raises questions about the inclusion of the axilla in the radiation field.