Acute pulmonary embolism (PE) is a common and often catastrophic disease. Early diagnosis and treatment of PE is im-portant, however, prompt diagnosis is difficult due to nonspecific clinical manifestations. On the other hand, syncope may develop as a presenting symptom of PE, and defecation activity could trigger PE. In Korea, PE associated with defecation has not been previously reported. We report on a case of acute massive PE presenting as defecation syncope in a 26-year-old female with a serous borderline tumor of the ovary.