Prostatic phyllodes tumor is an unusual lesion for which there are only occasional reports in the literature. We encountered a phyllodes tumor of the prostate in a 36-year-old man who had complained of urinary frequency and dysuria for one month. In October 1998, he visited our hospital and had a transurethral resection of the prostate (TUR-P) for obstructive symptoms. He experienced recurrent same symptoms in September 1999 and underwent another TUR-P. The pathologic examination at this time revealed phyllodes tumor. In the tumor, despite its regular alternating growth of ducts and stroma, the stromal element appeared histologically malignant, showing marked atypia and rhabdomyosarcoma-like components. Consequently, in December 1999, the patient underwent radical prostatectomy with lymph node dissection. The resection margins and pelvic lymph nodes were free of tumor. The patient remains alive and well after 14 months.