Abstract: Objective: To investigate the clinical value of digital subtraction angiography(DSA) diagnosis and interventional therapy for lower digestive tract hemorrhage of unknown cause.Methods: DSA was performed in 38 patients with lower digestive tract hemorrhage of unknown cause.The locations and causes of hemorrhage were determined by angiography according to the demonstration of contrast medium extravasation,abnormal vasculature and tumor staining.Infusion of vasopressin or embolization with spongia gelatinosa absorbentia and polyvinyl alcohol(PVA) were used after superselective catheter had been inserted in the bleeding artery.Results: Twenty-seven patients were positive in angiogram,17 patients of lower digestive tract hemorrhage caused by arterial venous malformation,6 by tumor,3 by intestinal diverticulm and 1 by caecum ulcer.Twenty-seven patients had been given the interventional therapy.In 17 of 27 patients that had been treated with infusion of vasopressin,13 patients stopped bleeding immediately(76%).In 10 patients with embolization,8 patients stopped bleeding immediately and 2 patients stopped bleeding after 24 hours.Conclusions: DSA and interventional therapy have important value in diagnosis and treatment of patients with lower digestive tract hemorrhage of unknown cause.