We report a case of progressive prostatic carcinoma in a patient with acquired hypogonadism. An 86- year-old man was admitted to our hospital complaining of weakened urinary flow. He had had hypophysectomy because of a pituitary tumor at 75 years old. Needle biopsy of the prostate showed poorly differentiated adenocarcinoma in the whole region and bone scan revealed bone metastasis of right scapula. The patient was treated with anti-androgen monotherapy because of secondary hypogonadism, but the prostate specific antigen score, continued to increase. Despite secondary anti-androgen and steroid therapy, he died 13 months after admission.