Transplantation is an established therapy for many hematologic disorders as well as for end-stage diseases of the kidney, lung, liver, heart among others. Osteoporosis and a high incidence of fragility fractures have emerged as a complication of organ transplantation. Many factors contribute to the pathogenesis of osteoporosis following organ transplantation. In addition, most patients have some form of bone disease prior to transplantation, which is usually related to adverse effects of end-stage organ failure on the skeleton. This chapter reviews the mechanisms of bone loss that occur both in the early and late post-transplant periods including the contribution of immunosuppressive agents as well as the specific features of bone loss after kidney, lung, liver, cardiac and bone marrow transplantation. Prevention and treatment for osteoporosis in the transplant recipient will also be addressed.