Multiple myeloma with gastrointestinal infiltration is rare, and it has been usually described in some case reports or case series. Stomach and small intestine are mostly involved, while large bowell involvement is very rare. Multiple myeloma should be considered in the differential diagnosis of some other diseases of the large bowel associated with weight loss, diarrhoea, malabsorption, frequent lumbar pain, effort intolerance. Colonoscopic biopsy followed by histopathological examination is essential for the diagnosis of multiple myeloma. Multiple myeloma with extramedullary infiltration of the colon has no well defined treatment guideline. Localised infiltration of gastrointestinal tract could be treated by surgical resection, but as these tumors are radiosensitive, radiotherapy has also been used. Chemotherapy with pulsed dexamethasone and afterwards a combination of cyclophosphamide, vincristine, melphalan and prednisone has been described in some case studies. Some patients were treated with other therapies incuding thalidomide, bortezomib, autologous or allogeneic stem cell transplantation. The clinical presentation, diagnosis and therapy may be challenging, so we present a 66-year old patient with extramedullary multiple myeloma of the colon who was treated at our Department.