Secondary spontaneous pneumothorax (SSP) caused by malignant tumors is rare, which often makes the choice of treatment difficult. In our hospital, we performed radical surgery for all pulmonary metastases arising from osteosarcoma (OS) in seven patients with SSP from February 1988 to February 2008 and retrospectively examined the clinicopathological features and postoperative outcomes. The common SSP etiology was tumor tissue rupture at the lung periphery. All patients died of OS recurrence within 18 months. A short disease-free interval (DFI) and a short interval to the second recurrence were the common clinical risk factors of poor prognosis. Curative surgery for pulmonary metastases in OS with SSP is unlikely, but in OS patients with peripheral metastatic lesions that are not accompanied by SSP and have a satisfactory DFI and few lesions, surgical resection should be strongly considered.