OBJECTIVE: This study aims to examine the role of surgery in patients with stage IV breast cancer. BACKGROUND: Historically, women who present with metastatic breast cancer are not offered surgical treatment. However, recent reports indicate that surgery may improve outcome. Using a large database of women whom presented with stage IV breast cancer, we compared outcome of patients who had resection of their primary cancer to those who did not. METHODS: Of 16,401 patients, 807 had stage IV disease at presentation, and 395 survived >90 days and were included in this analysis. Clinical and tumor characteristics, surgical treatment, and survival were compared for the surgically versus nonsurgically treated patients. RESULTS: Two hundred and forty-two patients (61.3%) had definitive surgery for their primary tumor and 153 (38.7%) did not. Patients who underwent surgery were significantly older, were more likely to be white, more often had hormone receptor positive disease, had small primary tumors, and had fewer metastatic sites and less visceral involvement. The median survival of surgically treated patients was 27.1 months versus 16.8 months for patients without surgical resection (P < 0.0001). In multivariate analysis, which included surgical treatment, age, race, estrogen and progesterone receptor status, number of metastatic sites, and presence of visceral metastases, surgery remained an independent factor associated with improved survival (P = 0.006). CONCLUSION: Patients with stage IV breast cancer who had definitive surgical treatment of their primary tumors had more favorable disease characteristics. However, after adjustment for these characteristics, surgical treatment remained an independent factor associated with improved survival.