We report the case of a 21-year-old man with antineutrophil cytoplasmic antibody (ANCA)--associated vasculitis who experienced spontaneous renal allograft rupture 21 months after engraftment. Because of chronic allograft nephropathy, the patient's immunosuppressive regimen had been discontinued approximately 3 weeks prior to his presentation with abdominal pain and evidence of internal hemorrhage. He was emergently taken to the operating room, where a ruptured allograft was found and transplant nephrectomy was performed. Postoperatively, the cause of rupture was determined to have been acute cellular rejection. This case may be the longest interval reported between renal transplant and spontaneous allograft rupture.