Carcinosarcoma is defined as a malignant tumor with an admixture of carcinoma and sarcoma. Pulmonary carcinosarcoma accounts for about 0.27 percent of all lung neoplasms. It occurs frequently in males, particularly in smokers between 50 and 80 years of age. Preoperative diagnostic tests, such as sputum cytology, percutaneous fine needle biopsy and bronchoscopy, have a low yield in detection of pulmonary carcinosarcoma. The diagnosis is verified by postoperative pathologic findings and by immunohistochemical investigations in many cases. Surgical resection is the treatment of choice. As the metastasis to regional lymph nodes and distant organ is common at diagnosed time, the prognosis is quite poor. We report a case of pulmonary carcinosarcoma presented with persistent mild fever and blood-tinged sputum in a 66-year-old male.