Background, Bone disease and fractures after organ transplantation pose severe clinical problems. About 20% of renal transplant patients have type 1 diabetes (IDDM). However, data are scarce in the literature about the occurrence of spontaneous fractures in IDDM patients posttransplantation. Methods. In this cross-sectional study using a questionnaire and hospital records the prevalence of symptomatic bone disease was investigated in 193 renal transplanted patients with functioning renal grafts 6 months to 23 years after the transplantation. Results, The frequency of IDDM was 18%. In the total group the rate of osteoporotic fractures posttransplantation was 17%, and the majority of fractures occurred within the first 3 years after the transplantation. A high rate of fractures, 40%, was noted in the diabetes group (P<0.001), compared with 11% in the nondiabetes group. Fractures seen in IDDM were often multiple and located mostly in the appendicular skeleton, i.e., in ankles and feet. Female gender was also associated with an elevated fracture rate, 23% (P<0.05). Conclusion. An increased incidence of osteoporotic fractures after renal transplantation was found in diabetic and female patients. The mechanism behind bone fragility in IDDM is multifactorial and despite a restored renal function bone disease may progress, and is probably enhanced by the immunosuppressive treatment.