Two kidneys were harvested from a cadaver donor and subjected to pulsatile perfusion in an identical fashion with a perfusate which was free of cytotoxic antibody. Classical 'hyperacute rejection' occurred in the right kidney when transplanted into a male patient with no previous blood transfusion or transplants, and repeatedly negative tests for cytotoxic antibody. The left kidney was not transplanted and was examined by light, electron, and immunofluorescence microscopy as was the immediately removed, transplanted kidney. Despite the absence of any immunological pathogenetic mechanism in the non-transplanted kidney, virtually identical changes of 'hyperacute rejection' were seen in both kidneys. Thus,even technically satisfactory perfusion may cause a syndrome of 'hyperacute graft failure' secondary to non-immunologically mediated perfusion injury.