IgA nephropathy has, in the course of two decades, become one of the most important renal diseases. Not only is it the most common form of glo- merulonephritis seen in many countries, its increasing recognition by renal biopsy in this time has allowed sufficient study to conclude that it is also one of the most frequent causes of end-stage renal failure. The clinical features are diverse, and only in a minority do recurrent macroscopic hematuric episodes associated with an upper respiratory tract infection allow a confident clinical diagnosis. All clinicians, from community practitioners to...