The neurological determination of death (NDD, brain death) is principally a clinical evaluation. However, ancillary testing is required when there are factors confounding the clinical determination or when it is impossible to complete the minimum clinical criteria. At the time of the 2003 Canadian Forum clarifying the criteria for brain death, 4-vessel cerebral angiography or radionuclide angiography were the recommended tests and the electroencephalogram was no longer supported. At the request of practitioners in the field, the Canadian Council for Donation and Transplantation sponsored the assembly of neuroradiology and neurocritical care experts to make further recommendations regarding the use of ancillary testing. At minimum, patients referred for ancillary testing should be in a deep unresponsive coma with an established etiology, in the absence of reversible conditions accounting for the unresponsiveness and the clinical examination should be performed to the fullest extent possible. For newborns, children and adults, demonstration of the absence of brain blood flow by following recommended imaging techniques fulfill the criteria for ancillary testing: 1. radionuclide angiography or CT angiography 2. traditional 4-vessel angiography 3. Magnetic resonance angiography or Xenon CT. In the absence of neuroimaging, an established cardiac arrest, as defined by the permanent loss of circulation, fulfills the ancillary criteria for the absence of brain blood flow. Acknowledging the existing limitations in this field, further research validating current or evolving techniques of brain blood flow imaging are recommended.