Osteosarcoma is the most common primary malignant neoplasm of the bone with over 60% of the cases occurring in patients 10-20 years old. Osteosarcoma rarely occurs in patients older than 40 years of age, most commonly in bones affected by preexisting conditions such as Paget's disease, prior irradiated bone or osteogenesis imperfecta. Osteosarcoma presenting with pleural metastases is very rare. Herein we describe a case of metastatic osteosarcoma presenting with pleural effusion due to underlying pleural metastases in a 55 year old woman.