Clinical manifestations of gastrointestinal (GI) involvement in multiple myeloma (MM) are uncommon. We report a case of plasmacytoma presenting as upper GI bleeding in a patient with a known diagnosis of MM. Gastrointestinal bleeding persists despite aggressive medical and endoscopic treatment. The aim of our report is to heighten the awareness of plasmacytoma as an etiology of GI bleeding in patients with MM. Abnormal hemostasis, specifically the imbalance in function of all major components of the coagulation cascade, increasing bleeding risk in patients with MM, is also discussed.