Testicular plasmacytoma, whether occurring as a primary lesion or as a reflection of underlying multiple myeloma (MM), is a rare disease. We report the case of a 38-year-old male with multiply relapsed MM, who was found to have a testicular plasmacytoma. He presented with a gradually enlarging scrotal mass. Following orchidectomy, pathologic examination of the specimen demonstrated a plasmacytoma. In the context of active MM, the specimen was also sent for cytogenetic analysis but this was unhelpful in guiding a chemotherapy regime, which still continues at time of reporting. Although a rare lesion, there remains no definitive treatment protocol for the management of testicular plasmacytoma representing an extramedullary manifestation of MM.