Spontaneous pneumothorax is a rare manifestation of primary lung cancer or metastasis. It is estimated that < 1% of all cases of spontaneous pneumothorax are tumor-associated and metastatic osteogenic or soft-tissue sarcomas are associated most commonly with pneumothorax especially in the setting of cytotoxic chemotherapy or radiotherapy. In this article, we report three pediatric cases with osteosarcoma that developed spontaneous pneumothorax during chemotherapy with a review of the literature. Two of them had lung metastasis at the time of the detection of pneumothorax and the remaining patient was found to have a bronchopleural fistula. SPx is an emergency situation and early diagnosis and management can improve prognosis and quality of life of the patient however the optimal management has yet to be determined.