Leiomyoma of the seminal vesicle is an extremely rare tumour. The diagnosis of this entity is important when it co-exists with prostatic carcinoma, since it call simulate tumour extension from prostate or bladder cancer on MR imaging and lead to overstaging. In this report. we describe a 74-year-old man with it leiomyoma of the seminal vesicle that mimics tumour extension from co-existent prostatic cancer oil T2-weighted MR imaging To our knowledge. this is the first description of imaging findings of concurrent leiomyoma of the seminal vesicle and prostatic carcinoma.