Recurrent or de novo diseases account for only 5% of graft failure in children, but have much to teach us about mechanisms. In children, almost the only metabolic disease with recurrence is type I hyperoxaluria, in which the poor long-term results of isolated renal transplantation makes combined liver and renal transplantation, or even prophylactic liver transplantation before renal failure the preferable alternative. While many forms of nephritis may show histological recurrence in allografts, it is notable that in many patients this is accompanied no clinical manifestations or only mild disease; this is particularly so in MCGN type II, IgA-associated nephropathy and Schonlein-Henoch. purpura. However, FSGS and MCGN type I recur with frequency and severity. Hemolytic-uremic syndromes may recur, even repeatedly, but this is unusual. As many as 10% of pediatric grafts may show de novo membranous nephropathy, but in the majority this is mild or not clinically evident. In contrast, the rare anti-GBM nephritis affecting some patients with Alport's syndrome usually results in graft failure, but occurs in only a minority of Alport recipients. For all types of disease in allografts, risk factors for recurrence are poorly worked out, and attempts at treatment generally ineffective.