Background: We conducted a retrospective analysis to evaluate the impact of omission of supraclavicular radiotherapy on supraclavicular failure rate and treatment outcomes in N1 breast cancer patients with evaluation of prognostic factors that affected supraclavicular recurrence free survival.Methods: This study analyzed the medical records of 109 patients with N1 breast cancer. All patients underwent surgery and received adjuvant chemotherapy without supraclavicular radiotherapy. Supraclavicular recurrence free survival, distant metastasis free survival, disease free survival, and overall survival were estimated using the Kaplan-Meier method and compared using log-rank analysis.Results: After a median follow up period of 58 months, treatment failed in 31 patients (28.4%); patterns of failure consisted of locoregional (n=21, 19.3%), isolated supraclavicular (n=7, 6.4%), and distant metastasis (n=14, 12.8%). Survival rates at 5 years were as follows: supraclavicular recurrence free survival (84.9%), distant metastasis free survival (87.6%), and overall survival (86.4%). Univariate analysis revealed that the type of chemotherapeutic regimen was the only significant prognostic factor affected supraclavicular recurrence free survival; patients who received the cyclophosphamide, methotrexate, 5-fluorouracil chemotherapy regimen experienced lower supraclavicular recurrence free survival than those who received doxorubicin based and taxane based chemotherapy. Development of supraclavicular recurrence significantly lowered the 5-year overall survival (57.1%) and distant metastasis free survival (50%) rates compared to patients without supraclavicular recurrence who had an overall survival rate of 88.5% (P<0.0001) and distant metastasis free survival rate of 90% (P<0.0001).Conclusion: Patients with N1 breast cancer had an overall supraclavicular recurrence of 6.4% which denoted that additional supraclavicular radiotherapy was unnecessary and could be given in N1 patients after surgery and an adjuvant CMF regimen. A prospective randomized trial would be needed to clarify the impact of supraclavicular radiotherapy on treatment outcome.