Amyloidosis is a disorder characterized by extracellular deposition of amyloid in various tissues and organs. Gastrointestinal manifestations including gastroparesis, constipation, malabsorption, intestinal pseudo-obstruction, and bleeding are common. GI bleeding is a rare initial symptom which can be fatal in some cases. Absence of systemic symptoms and nonspecific endoscopic findings in amyloidosis may make diagnosis difficult. Therefore, amyloidosis-induced GI bleeding should be considered in patients with an obscure hemorrhage. Recently, we experienced a 65-year-old woman who presented with massive hematochezia as a manifestations of amyloidosis. Colonoscopy and SMA angiography showed massive bleeding in the small and large intestine. Colonoscopic biopsy established amyloidosis. We report this case with a review of the relevant literatures.