Tranexamic acid has been therapeutically used in various clinical conditions with bleeding. However, this drug might carry a risk of thrombosis as an adverse effect. We report a patient who developed left popliteal artery thrombosis after the administration of tranexamic acid for the treatment of upper gastrointestinal bleeding. A 96-years-old woman with gastric cancer was admitted to our hospital because of an ischemic stroke. She had severe anemia, and received a blood transfusion. To control the bleeding, a single dosage of tranexamic acid (1, 000mg/day) was administered. Twelve hours after the administration of the drug, she suffered an acute obstruction of the left popliteal artery. Tranexamic acid is frequently used to control gastrointestinal bleeding. However, no definite evidence exists confirming that tranexamic acid is useful for gastrointestinal bleeding. The inhibition of fibrinolysis by tranexamic acid is not considered to be safe in patients with a hypercoagulable state, and the use of tranexamic acid should be carefully determined on an individual basis.