Sixteen cases of first pulmonary metastasis from breast cancer were reexamined. There was no significant difference between the operated and non-operated cases. The prognoses of both groups were unfavorable due to aggravation of the lung, including the pleural focus or other distant metastases. We found a surgical benefit in only selected cases such as comparatively advanced breast cancers with long disease-free intervals, and cases in which the differentiation with the primary lung cancer was difficult. We recommend a mildly invasive operation using video-assisted thoracic surgery in these cases.