In contrast to the decreasing incidence of pulmonary thromboembolism in Western countries, the incidence examined as determined by autopsy, vital statistics, and clinical surveys is increasing in Japan. The combination of these data indicates the possibility of low diagnostic ability in Japan. The causes of the disease and the predictors of in-hospital death are summarized. The most popular congenital coagulopathies in Western countries, factor V Leiden and prothrombin G20210A mutation, have not been found in Japan. But recent reports showed that coagulopathy might have a greater contribution to the occurrence of the disease than was previously thought. We introduce reports that show a relation between the disease and life style.