Osteoporosis following allogenic organ transplantation represents an increasingly common medical and socioeconomic problem. Contributing factors include hospitalization, long-term immobilization, and usage of immunosuppressive drugs (glucocorticoids, cyclosporine A) in patients who undergo transplantation. In addition, complications of underlying diseases and adverse effects of drugs used in their management such as glucocorticoids, laxatives, loop diuretics, and heparin may promote the development of posttransplant osteoporosis. Consideration of individual risk factors involved in the pathogenesis of posttransplant osteoporosis is mandatory for appropriate prevention and treatment.