Abstract: Objective:To assess the clinical characteristics, treatment and prognostic factors of solitary pulmonary me -tastasis (SPM) in breast cancer patients. Methods:From January1999 to January 2009, 35cases of patients with solitary pulmonary nodule (SPN) were treated at our center. All of the patients had a history of breast cancer and underwent sur-gery for an SPN. Results: The median time from mastectomy to SPN was48months (range, 6~177 months). The histology of SPN revealed pulmonary metastasis of breast cancer in 21(60%) patients, primary lung cancer in 8 (22.9%) patients, and benign condition in 6 (17.1%) patients. In the21with solitary pulmonary metastasis (SPM) of breast cancer, the2, 3 and 5-year survival rates after pulmonary mastectomy were 95.2%,71.4% and 19.0%, respectively. The median progress free survival (PFS) from the pulmonary mastectomy to progress was 32months, and the median survival time after surgery of SPM was 43months (range, 12~103 months). Chemotherapy after pulmonary mastectomy was the strongest predictor of outcome by univariate analysis. Other factors included the initial size of breast tumor, the lymph-vascular invasion and time to SPN > 60months. Conclusion:Patients with SPN are a heterogeneous group. For patients with lung metastasis of breast cancer, the surgical approach should be the diagnosis and treatment of choice. For patients with pulmonary metasta-sis of breast cancer, the systemic treatment after pulmonary mastectomy may give an optimistic prognosis.