Purpose: To analyze the results of locoregional and systemic therapy in the breast cancer patients with locoregional recurrence (LRR) after mastectomy. Materials and Methods: Seventy-one patients who received radiotherapy for isolated LRR after mastectomy between January 1999 and December 2009 were retrospectively reviewed. Among the 71 patients, 59 (83.1%) underwent wide excision and radiotherapy and 12 (16.9%) received radiotherapy alone. Adjuvant hormonal therapy was given to 45 patients (63.4%). Oncologic outcomes including locoregional recurrence-free survival, disease-free survival (DFS), and overall survival (OS) and prognostic factors were analyzed. Results: Median follow-up time was 49.2 months. Of the 71 patients, 5 (7%) experienced second isolated LRR, and 40 (56%) underwent distant metastasis (DM). The median DFS was 35.6 months, and the 3- and 5-year DFS were 49.1% and 28.6%, respectively. The median OS was 86.7 months, and the 5-year OS was 62.3%. Patients who received hormone therapy together showed better 5-year DFS and OS than the patients treated with locoregional therapy only (31.6% vs. 22.1%, p = 0.036; 66.5% vs. 55.2%, p = 0.022). In multivariate analysis, higher N stage at recurrence was a significant prognostic factor for DFS and OS. Disease free interval (${leq}30$ months vs. >30 months) from mastectomy to LRR was also significant for OS. The patients who received hormone therapy showed superior DFS and showed trend to better OS. Conclusion: DM was a major pattern of failure after the treatment of LRR after mastectomy. The role of systemic treatment for LRR after mastectomy should be investigated at prospective trials.