Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma in adults. However, primary MFH of the lung is rare, with only a few cases reported in the literature. Here, we report the case of an 86-year-old male who was admitted to our hospital with the chief complaint of exertional dyspnea and poor appetite. Chest roentgenography revealed a 9 x 15 cm, pleural-based opacity in the left lower lobe. Chest computerized tomography disclosed a well-defined mass with heterogeneous density in the left lower lung field. The diagnosis of MFH was confirmed by thoracoscopic lung biopsy and pathologic examination. Supportive care was given because of extreme old age and poor performance status (the patient's Karnofsky performance status was 30). The patient died from respiratory failure 2 months later.