A 58-year-old woman was referred to our hospital with a chief complaint of exertional dyspnea. Bronchoscopy failed to establish a diagnosis, and the patient subsequently died suddenly due to respiratory insufficiency because of advanced pulmonary hypertension (PH). The pathological diagnosis at autopsy was pulmonary veno-occlusive disease (PVOD). PVOD is difficult to diagnose antemortem and has a poor prognosis. Lung transplantation is the only curative treatment for PVOD.