Membranoproliferative glomerulonephritis is a chronic glomerulopathy with a generally progressive course toward end-stage renal disease and a high recurrence rate in renal allografts. Described herein is the appearance of rapidly progressive glomerulonephritis (crescentic glomerulonephritis) in the course of type I membranoproliferative glomerulonephritis. This transition occurred within 6 weeks, documented histologically by an initial and subsequent renal biopsy. No recurrence of the disease was noted in a living donor graft 18 months posttransplantation.