We report three patients with well-documented renal amyloidosis who developed rapidly progressive renal failure. Renal biopsies from all three patients showed crescentic glomerulonephritis imposed on renal amyloidosis. All patients were treated with intravenous high-dose methylprednisolone pulses combined with immunosuppressive agents and oral corticosteroids. Partial recovery of renal function was obtained in two patients. For the third patient, treatment had to be stopped after a few days because of a septic arthritis. Renal function continued to deteriorate, and the patient had to be placed on regular hemodialysis. We conclude that extracapillary glomerulonephritis may occasionally complicate a preexisting renal amyloidosis and may be reversible if recognized early and treated appropriately.