Purpose To study the clinicopathologic features, differential diagnosis, immunophenotype and treatment and prognosis of adult intratesticular rhabdomyosarcoma ( ITRMS) . Methods One case of adult ITRMS was analyzed by histology and immunohisto-chemistry, the date of treatment and prognosis through electronic medical record. The published relevant literatures were reviewed. Re-sults A 19-years old male patient was admitted to the hospital with a history of 2-months testicular painless enlargement. Testis ultra-sound examination and scrotal and abdominal CT revealed a mass in right testis. Macroscopic observation of the testis showed that a grey-white tumor. The tunica albuginea, epididymis and spermatic cord hadn’ t been invaded by the tumor. Microscopically, medium-size oval or round cells were arranged in sheets, and spindle-shaped, strap-like, large-circle cells were also presented. Few large cells had abundant granular eosinophilic cytoplasm with crossstriations under oil immersion objective. Immunohistochemically, the tumor cells were positive for vimentin, HHF35, desmin, MyoD1, Myogenin and h-Caldesmon protein, more than 50% neoplasm cells were positive. The rate of Ki-67 was 75%. Conclusions Adult ITRMS is rare. Histologically, embryonal rhabdomyosarcoma ( ERMS) is the most common type. They have highly invasive and poor prognosis. The accurate diagnosis depends on the combination of the histo-logic and immunohistochemical examination.