The effects of androgen deprivation therapy (ADT) include not only suppression of tumor growth but also adverse effects on various bodily functions. The aim of this study was to determine the metabolic effects of ADT in patients with non-metastatic prostate cancer. Forty-nine men with prostate cancer were treated with ADT before beginning radical therapy for six months. Body weight, peripheral red blood cell counts, hemoglobin, hematocrit, fasting blood sugar, serum total cholesterol, blood urea nitrogen, uric acid, compensated calcium, inorganic phosphorus, bone specific alkaline phosphatase, urine deoxypyridinoline, and the radial bone density using dual energy x-ray absorptiometry were examined before and six months after ADT. Body weight (P = 0.037) and the levels of fasting blood sugar (P = 0.014), serum total cholesterol (P = 0.017), blood urea nitrogen (P = 0.030), compensated calcium (P < 0.001), inorganic phosphorus (P < 0.001), bone-specific alkaline phosphatase (P < 0.001), and compensated urine deoxypyridinoline (P < 0.001) increased significantly. Peripheral red blood cell counts (P < 0.001), hemoglobin level (P < 0.001), hematocrit (P < 0.001), uric acid (P < 0.001), and the radial bone density (P = 0.023) decreased significantly. These effects of ADT on various bodily functions warrant systematic study in clinical trials. We should be aware of the far-reaching consequences of ADT and should incorporate strategies for preventing and managing adverse effects into routine practice.