Almost all forms of glomerulonephritis affecting the native kidney may recur in the transplanted kidney. However, in a large majority of patients, recurrent glomerulonephritis has only a minimal impact on graft function and survival; less than 5% of all graft losses are the result of recurrence. Kidney transplantations provide an attractive experimental model for investigating the pathophysiological mechanisms in diseases, such as diabetes, in which the recurrence of glomerulonephritis is frequent, and segmental glomerular sclerosis in which glomerulonephritis is severe.