A study investigating causes of kidney transplant failure reports that antibody-mediated rejection is the major cause of renal allograft failure after a biopsy for clinical indications, and highlights the importance of nonadherence in rejection. In total, 60 of 315 renal allograft recipients who had undergone biopsy for clinical indications (6 days to 32 years after transplantation) progressed to failure. Among 36 patients with rejection, 17 (47%) had been identified as being nonadherent to immunosuppressive medications.