Osteoporosis is an important complication of androgen deprivation therapy (ADT). ADT by either orchiectomy or treatment with a gonadotropin-releasing hormone agonist decreases bone mineral density and increases fracture risk. Other factors, including diet and lifestyle, may contribute to bone loss in men with prostate cancer. Routine osteoporosis screening in men with prostate cancer is appropriate based on the high prevalence of osteoporosis. There is limited information about the best strategy to treat or prevent bone loss during ADT. Lifestyle modification, including smoking cessation, moderate alcohol consumption, and regular weight-bearing exercise should be encouraged. Supplemental calcium and vitamin D are also recommended. Additional treatment is warranted for men with osteoporosis, fractures, or high rates of bone loss during ADT. Pamidronate, an intravenous bisphosphonate, prevents bone loss during ADT. Other bisphosphonates are probably effective, although they have not been evaluated in this clinical setting. Alternative forms of hormonal therapy, including bicalutamide monotherapy, may cause less bone loss than ADT.