Introduction: Irreversible absence of cerebral and brainstem functions defined as brain death. The criteria for brain death includes a patient in a comatose state, absence of brain stem reflexes on neurologic examination, and a core body temperature >90°F. Assessing brain death may sometimes be difficult especially when a discrepancy between the clinically and EEG-assessed brain death is presented. This may lead to misdiagnosis of brain or brain stem death. Nuclear medicine techniques were used to support the diagnosis of brain death. Uptake of Tc99mHMPO in the cerebral and cerebellar cortices was detected in patients suspicious of the brain death. Nuclear imaging demonstrated an absence of intracerebral uptake of the tracer in patients with brain death. In patients with severe closed head injuries, a nuclear medicine perfusion test revealed the lack of uptake of radionuclides in the neocortex. Conclusion: Nuclear medicine tests as well as a non-contrasted CT scan or computed tomographic angiography can be also performed at the same time with minimal additional risks to evaluate the lack of blood flow to the brain and improve our diagnosis of the brain death.