A 35-year-old male patient presented with a 1-year history of hesitancy in voiding. An urethrogram revealed urethral stricture, therefore an urethrotomy with biopsies was performed. Histologic results suggested the diagnosis of extramedullary mature plasmocytoma.After external beam radiotherapy with a total dose of 45 Gy the patient is disease-free without any therapy-related late effects after a follow-up of 36 months.Primary localization of extramedullar plasmocytomas in the genitourinary tract is very rare. This case report discusses a case of a male patient suffering from plasmocytoma of the urethra, who could be treated successfully by primary external beam radiotherapy.