Abstract: Objective This study was designed to explore the value of multi-slice spiral CT in the diagnosis of vertebrobasilar dolichectasia(VBD). Methods The diameter,the bifurcated height and transverse position of basilar artery(BA) on multi-slice spiral brain CT images of 2658 patients were measured to find out vertebrobasilar dolichectasia cases by according to the definition of WR Smoker,et al. Results The basilar artery could be demonstrated clearly in 2379 out of 2658 on multi-slice spiral CT images which were obtained by reconstruction at 3mm slice thick using images of 8mm slice thick.16 vertebrobasilar dolichectasia cases accorded with diagnostic criteria outlined by WR Smoker et al were found,and the CT finding and clinical representations were similar to those reported in the literatures. Conclusion 89.50 % basilar artery could be displayed on multi-slice spiral brain CT images according to the methods mentioned,then vertebrobasilar dolichectasia could be diagnosed.