Diabetic nephropathy (DN) develops in approximately 40% of type 1 diabetic patients and is a leading cause of end-stage renal failure. Its rate of progression varies greatly among individuals. Several factors, including genetic predisposition, metabolic and haemodynamic alterations and various growth factors, may contribute to the initiation and progression of DN. The genetic background of DN is believed to be polygenic. Polymorphisms of different genes, mainly from the renin-angiotensin system, have been studied extensively, and some of them have been suggested to contribute to the development of DN. A search for genes and combinations of genes which could influence the development and progression of DN is in progress.