The aim of this study was to assess the frequency and clinical implications of a recurrence of the original renal disease in children after kidney transplantation. Thus, the records of patients with immunological and metabolic diseases transplanted between 1970 and 1994 were retrospectively analyzed. There were 113 renal transplantations in 99 patients, who had the following original diseases: focal segmental glomerulosclerosis (FSGS), membrano-proliferative glomerulonephritis type I and type II (MPGN I, II), Henoch-Schoenlein nephritis, IgA-nephropathy, hemolytic uremic syndrome (HUS) and hyperoxaluria type I (PH I) and other rare diseases. Recurrences were observed in FSGS, MPGN II, HUS and PH I but not in the other diseases. In FSGS, the recurrence rate was 20% with graft failure in 5 of 6 grafts. No specific risk factors for recurrent FSGS could be determined. In MPGN II, the recurrence was 60% but the loss of grafts occurred at the same rate as in the non-recurrence group. In HUS, recurrence was seen in 4 out of 24 renal grafts (16.6%) with subsequent graft loss in all cases. All cases had suffered from an atypical HUS. PH I recurred in 4 of 5 allografts with graft loss in all patients. The remaining graft was transplanted after a liver transplantation and graft function was well preserved for 4 years. We confirm that the risk of recurrence with loss of the graft is high in a certain group of renal diseases. In these the indication for transplantation, particularly with living related donor kidneys, needs special evaluation. A better understanding of the pathomechanism of the diseases should lead to prevention of recurrence, as in PH I in which a liver transplant is now the primary option.