In spite of clinical practice guidelines such as the National Cancer Institute (NCI)-Physician Data Query (PDQ), in which primary androgen deprivation therapy (PADT) is not recommended at all as the primary treatment for localized prostate cancer, many such patients have actually been treated with PADT in Japan. The reasons are probably that medical treatment such as PADT is more acceptable than more invasive treatments such as surgery for many Japanese patients, and that urologists themselves have also conform to their patient's wishes for the treatment, because they know the effectiveness of PADT in their experiences. In this review, we note clinical trials in which the efficacy of PADT for localized or locally advanced prostate cancer is demonstrated. Then, we discuss which patients are candidates for PADT, and show that more than 30% of low- or intermediate-risk localized prostate cancer can be controlled long term with PADT. Although the duration of PADT is also discussed, short-term or intermittent PADT cannot be recommended, because cancer cells which can be controlled for a long-term period or cancer that may appear to be cured by appropriate PADT may progress to cancer cells with more malignant potential with incomplete androgen ablation. We propose algorithms for the treatment of localized prostate cancer not only in low- and intermediate-risk groups but also in the high-risk group. Although the side effects of PADT affecting the healthy status of prostate cancer patients may not be serious, as reported in several studies, adverse effects caused by ADT on physical and mental conditions, such as osteoporosis and anemia, should be overcome by adequate treatment. Ideally, new hormonal compounds targeted only for prostate cancer will be developed.