Testicular plasmocytomas are rare neoplasias that may occur as isolated tumors or in concomitance with a multiple myeloma. We report the case of a 47-year-old man with previous history of multiple myeloma. He presented with persistant fever and right testicular mass which was confirmed by scrotal sonography examination. A right orchiectomy was performed. The histological examination showed a plasmocytoma and immunohistochemical stains revealed monoclonal light chain lambda in tumor cells.