PURPOSE: To evaluate the diagnostic value of source images of 3D TOF MR angiography in patients with hemifacial spasm. MATERIALS AND METHODS: Thirteen patients with surgically-confirmed hemifacial spasm and 30 who were not suffering from this condition were included in this study. T1 and T2-weighted images and 3D TOF MR angiography were performed. In 43 randomly-selected individuals, we retrospectively determined whether source images obtained during 3D TOF MR angiography could be used to evaluate symptoms. The results were correlated with surgical findings. RESULTS: Sensitivity was 92% and specificity was 86%. In all 13 patients with hemifacial spasm, neurovascular compression was detected during their operation. Offending vessels were the anterior inferior cerebellar artery (AICA) in four cases, the posterior inferior cerebellar artery (PICA) in seven, both the vertebral artery and PICA in one, and the vertebral vein, also in one. There were ten false-positive cases in the asymptomatic control group, nine of which showed neurovascular contact in the root entry zone of the facial nerve; one case showed indentation of the pons. CONCLUSION: Source images obtained during 3D TOF MR angiography are useful in the preoperative evaluation of hemifacial spasm.