The aim of this study was to facilitate the diagnosis of brain death based on semi-quantitative parameters as well as the other scintigraphic signs and symptoms of brain death. Altogether, 72 studies were performed in 54 patients (35 males, 19 females) to evaluate the diagnoses of brain death which were confirmed in 49 cases. Perfusion dynamic acquisition and static imaging were performed after the intravenous injection of 700-900 MBq 99Tcm-hexamethylpropyleneamine oxime (HMPAO). We reviewed the following parameters retrospectively: (1) qualitative visual assessment of the presence or absence of delayed HMPAO deposition in the brain area; (2) qualitative visual assessment of a 'three-pronged fork' of the cerebral arteries during the first-pass study; (3) any evidence of 'hollow skull' during the first-pass study; (4) any evidence of 'hot nose'; (5) blood flow index (i.e. the ratio of the area under the brain time-activity curve vs that under the curve for the carotid arteries); and (6) delayed uptake index (i.e. the ratio of HMPAO deposition in the brain vs that in the facial regions of interest). We were able to demonstrate the validity of individual signs and symptoms and to confirm the highly reliable nature of semi-quantitative scintigraphic parameters.