A 74-year-old man was referred to our clinic for the work-up of digitally hard and irregularly surfaced prostate and elevated serum prostate-specific antigen (PSA). His serum PSA was elevated to 41 ng/ml, but testosterone and LH level were decreased to 23.5 ng/dl and 0.5 mIU/ml, respectively. He had a history of taking an androgenic medicine containing methyl-testosterone 2 to 3 times a week for 2 year and 6 months. Transrectal sextant prostatic biopsy revealed moderately differentiated adenocarcinoma (Gleason score: 3 + 4) in 6 of 6 specimens and CT scan of the abdomen showed an enlarged obturator lymph-node (15 mm), resulting in the diagnosis of stage D1 (T3aN1M0) prostate cancer. Since serum testosterone level seemed to recover around the normal level after discontinuation of the exogenous androgen, we treated him with combination androgen blockade with LHRH agonist and bicaltamide, although his testosterone level was very low. Indeed, serum PSA decreased to 0.09 ng/ml and the right obturator node was markedly reduced by the hormone treatment. After the neoadjuvant therapy of 6 months duration, radical prostatectomy and limited pelvic lymph node dissection was carried out. Histologically, viable cancer cells were not found in any of resected lymph nodes, but they remained in bilateral lobes of the prostate (pT2bN0). The histological effect of the neoadjuvant hormone therapy according to General rule for Clinical and Pathological Studies on Prostate Cancer (3rd ed.) was grade 2. The patient has been well with undetectable PSA and no evidence of clinical failure for more than 12 months, though serum testosterone level recovered to near normal (288 ng/dl) 8 months after the cessation of the hormone treatment following the operation. Combination androgen blockade or non-steroidal anti-androgen agent appears to be effective for the treatment of prostatic cancer patients who takes exogenous androgenic medicine, even with a suppressed low serum testosterone level.