A 77-year-old man who had undergone low anterior resection suddenly lost consciousness when he tried to leave his bed on postoperative day (POD) 4. He exhibited dyspnea, cyanosis, and shock, and 4.8×10⁵ units of urokinase (i.v.) was given immediately after the onset based on a diagnosis of acute pulmonary thrombo-embolism (PTE). The diagnosis was confirmed by CT and an arteriogram that showed multiple emboli and cutoff signs in branches of the pulmonary arteries. A Greenfield catheter was introduced into the IVC to prevent re-embolism, and anticoagulant therapy with urokinase and heparin was carried out for 5 days and followed by oral warfarin. The patient recovered from the attack and left the hospital symptom-free on POD 21. The incidence of postoperative PTE in Japan has recently been increasing, and thus prevention of postoperative PTE should be considered, especially for high risk patients, such as elderly, obese, and cancer patients.