Spontaneous pneumothorax (SP) is a very rare condition, mainly seen in patients with underlying lung diseases. Pneumothorax caused by lung metastasis occurs in 1% of whole spontaneous pneumothorax cases, especially in the setting of cytotoxic chemotherapy or radiotherapy. The most frequently involved tumor is osteogenic sarcoma. But, before initiation of chemotherapy, spontaneous pneumothorax as a complication of malignancy is rare. Herein, we report a case of spontaneous pneumothorax in a 19-year-old female with osteosarcoma of left ilium. The patient was not receiving chemotherapy or radiotherapy and was found to have pneumothorax at the initial presentation, which is rare. Chest CT revealed bilateral pulmonary metastases and right sided pneumothorax.