Observation of serial pulmonary scintigraphies after the treatment in the patients with pulmonary thromboembolism revealed altered perfusion in the lung area unaffected by embolism in 2 cases. Also, showed that recovered perfusion of the embolized lung area influenced the perfusion of contralateral embolic lung area in 1 patient. These findings were detected and confirmed by comparison of the serial scintigraphies mutually. These results indicate that the serial scintigraphy is useful not only for assessing perfusion recovery but also for detecting altered perfusion in the lung area unaffected by the embolism.