We report a rare case of multiple myeloma that developed extramedullary plasmacytoma at the hilus of the liver causing obstructive jaundice. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy was quite useful in the diagnosis. A 71-year-old man was diagnosed with stage IIIA multiple myeloma in June 2007 based on osteolytic lesions, increased atypical plasma cells in the bone marrow, and monoclonal (M) protein of IgA-lambda, IgG-lambda, BJP-lambda type. M-protein was decreased by MP therapy following radiotherapy for the cervical lesion. However, in February 2008, M-protein started to increase again. The patient presented with obstructive jaundice in the middle of March. Abdominal ultrasound and MRI demonstrated a 12-mm mass at the hilus of the liver and the upper biliary tract dilatation, and a stent was placed across the bile duct stricture. EUS-FNA biopsy from the hepatic hilar mass showed multiple sheets of atypical plasma cells consistent with extramedullary plasmacytoma. The abdominal and intracranial mass did not respond to bortezomib therapy and gradually developed. Radiotherapy and high dose dexamethazone therapy were performed with little effect. The patient died in June 2008. To our knowledge, this is the first reported case of extramedullary plasmacytoma diagnosed by EUS-FNA.