A 27-year-old male was admitted to our hospital with the chief complaint of dyspnea. Radiologically, he was found to have a large tumor shadow in the left hemithorax with pleural effusion. The first thoracotomy was done to resect the tumor on January 14, 1988. The second and third thoracotomies were done because of local recurrence in the left hemithorax. Histological diagnosis was of a hmangio-pericytoma. Before the third operation, Ga-67 scintigraphy was performed. Ga-67 accumulation was noted in parts of the tumor mass. Histological findings of the resected tumor were compared with the degree and location of Ga-67 accumulation. Histologically, Ga-67 accumulation occurred in areas of bleeding and necrosis in the tumor tissue, but not in viable parts of the tumor. Ga-67 accumulation usually occurs in viable tumor cells, but our findings were contrary to this generality.