Surgical or chemical castration is widely used for the treatment of advanced prostate cancer. Common side effects of castration are e.g. sweating, increased body fat, decreased muscle mass, impotency and anemia. Castration increases the risk of osteoporosis and fractures in prostate cancer patients via hormonal effects to the bone. Castrated men should be recommended to increase physical activity. Calcium and vitamin-D supplementation is recommended. The European Association of Urology guidelines for prostate cancer recommend bone mineral density measurements before long-lasting castration therapy. Medical therapy should be considered for patients after low-energy fractures, after the diagnosis of osteoporosis based on bone mineral density measurements and for fracture high-risk patients based on clinical decision.