• Five children had rapidly progressive glomerulonephritis, determined by biopsy specimen and terminating in end-stage renal disease. All had mesangial deposition of IgA and C3 in the pattern typically seen with IgA nephropathy (Berger's disease). These children ranged in age from 7 to 13 years; four were boys. Severe hypertension was present in all, and three had a nephrotic syndrome. Other than hypertension and findings related to renal insufficiency or nephrotic syndrome, no clinical or laboratory finding was a consistent marker distinguishing these patients from those with uncomplicated IgA nephropathy, and no therapy proved useful in halting the rapid decline in renal function. The disease has not recurred in the kidney transplant of any of the five children.