Alveolar soft part sarcoma (ASPS) is a rare malignant soft-tissue neoplasm of unknown histogenesis. The two main sites of occurrence are the lower extremities in adults and the head and neck in children. We report the first case of pleural ASPS occurring in a 58-yr-old man who presented with progressive dyspnea. A computed tomographic scan of the thorax revealed a large enhancing pleural mass with pleural effusion in the left hemithorax. Wide excision of the pleural mass was performed. Histologically, the tumor consisted of organoid nests of large polygonal cells, the cytoplasm of which had eosinophilic and D-PAS positive granules. Immunohistochemical staining showed that the tumor cell nuclei were positive for transcription factor 3 (TFE3). The pleural ASPS with multiple bone metastases recurred 1 yr after surgery and the patient died of acute pulmonary embolism 1.5 yr after diagnosis.