BACKGROUND The diagnosis of brain death is based on both clinical and laboratory findings. However, diagnosis of brain death is still contentious and reliable tests are required. Early recognition and declaration of the diagnosis is the main goal, which is important for discontinuation of life support and organ donation for transplantation. In order to achieve this goal, competent diagnostic procedures should be performed. In this paper the authors review the diagnosis of brain death in eight children from different age groups, with an emphasis on factors concerning the reliability, use and appropriate application time of Tc-99m-HMPAO single photon emission computed tomography (SPECT) in early diagnosis in infants and newborns. METHODS Eight patients who fulfilled the clinical criteria of brain death underwent Tc-99m HMPAO SPECT and electroencephalogram (EEG) monitoring. RESULTS All patients had electrocerebral silence on EEG recordings. Six patients showed lack of perfusion in cerebrum in their first SPECT, however, newborns needed a second image for a confirmed diagnosis. CONCLUSIONS In infants, SPECT has a high reliability for confirmed diagnosis of brain death; however, in newborns the application time is important for an accurate diagnosis.