Prostatic carcinoma is exceptional in young adults before the age of 30. It is often diagnosed at a late, clinically advanced stage with a poorly differentiated histological type. Treatment is usually palliative and the prognosis is very poor with a mean survival of 6 months. The authors report a new case in a 25-year-old patient with locally advanced poorly differentiated prostatic carcinoma and a Gleason score of 10 treated by endocrine therapy, radiotherapy and chemotherapy with a good clinical and radiological course with a follow-up of two years.