A 32-year-old woman was hospitalized with recurrent left-sided chest pain and dyspnea on exertion, which had progressed for approximately 10 years. Since age 18 she had been spending more than twelve hours per day in a predominantly seated position on a floor mat, engaged in Japanese dressmaking. A chest roentgenogram showed marked dilation of the main pulmonary arteries, bilateral oligemia in the upper lung fields and a peripheral infiltration in the middle field of the left lung. The (99m)Tc-MAA perfusion lung scan showed multiple defects in both lungs, but no abnormal findings were detected on a 133Xe ventilation scan. A pulmonary angiogram showed multiple occlusions of pulmonary arteries in both lungs. Because recurrent chest pain and dyspnea had been present for a long time, and because ultrasonic cardiography revealed pulmonary hypertension repeatedly for several years, pulmonary thromboembolism was considered to be chronic and recurrent. The patient had none of the following risk factors for pulmonary emboli: malignancy, neurological disease, heart disease, obesity, pregnancy, or a congenital coagulative abnormality such as deficiency of AT-III, protein C, protein S, or plasminogen. Because no other cause could be found, the chronic recurrent pulmonary thromboembolism most likely resulted from extensive sedentary work that caused stagnation of venous return and deep vein thrombosis.