A case is reported of osteosarcoma of the 11th rib in a 38-year-old woman who presented with dry cough and dyspnea due to bloody pleural effusion and the literature on osteosarcoma of the rib in Japan is reviewed. Osteosarcoma was suggested by roentgenologic findings and examination of a percutaneous needle biopsy specimen. Therefore, we administered chemotherapy, but the tumor showed progressive expansion and invasion, causing paraplegia. The patient died on the 282nd day of admission. We performed an autopsy and diagnosed osteosarcoma histologically. The tumor was covered by a hypervascular capsule, suggesting its association with the bloody pleural effusion. Osteosarcoma of the rib has not been previously reported in association with bloody pleural effusion. Considering the prognosis and characteristics of such tumors, we recommend prompt diagnosis in cases presenting with bloody pleural effusion.