The Danish study group for metabolic studies after transplantation of the pancreas. Development of combined pancreatic and renal transplantation and transplantation of islet cells in the treatment of insulin-dependent diabetes mellitus is reviewed. Transplantation of the pancreas is undertaken in Denmark on the indication of diabetes mellitus complicated by terminal diabetic nephropathy in patients who are considered, in advance, as candidates for renal transplantation. During recent years, improved results have been obtained by combined pancreatic renal transplantation with patient survival of up to 96% and graft survival of up to 84% after two years. Despite normal HbA1C, the intermediate metabolism is abnormal after combined pancreatic and renal transplantation. At present, it does not appear to prevent or arrest development of diabetic retinopathy while the results indicate that progression of diabetic nephropathy and neuropathy can be halted. Development in islet cell transplantation is promising. As yet, there has only been limited success with transplantation of foetal islet cells and this also involves great ethical problems. Xenographic transplantation of foetal islet cells may be of current value in the future. During recent years, 20% of islet cell transplantations from adult human donors have resulted in insulin independence for briefer periods (maximal 24 months, January 1992). Improved methods have been developed in immune modulation, immune isolation and cryopreservation and these make purification and harvesting of adequate quantities of islet cell mass possible to obtain exogenic insulin independence. Development of new immune suppressives has not improved the results. In the future, islet cell transplantation will possibly become part of the treatment of insulin-dependent diabetes mellitus.