The cause of end-stage renal failure in one-third of patients treated by regular haemodialysis or kidney transplantation is some variety of glomerular disease. Less serious glomerular dis orders are more common and often cause inappropriate conster nation to the patients and, sometimes, to their doctors. Similar clinical features can be produced by pathological lesions ranging from the trivial to the life-threatening, and renal biopsy is often necessary to establish the diagnosis. However, its widespread use during the past 20 years has enabled clinicopathological correlations to be made and...