Objective To assess the diagnostic value of MSCT in congenital bridging bronchus (BB).Methods Three-dimensional (3D) reconstructed CT images including MPR,MinIP,MIP,VR were respectively analyzed in 12 patients with congenital bridging bronchus on postprocessing workstation.Results Six of 12 BB patients were type Ⅰ bridging bronchus which originated from the left main bronchus at the level of fourth and fifth thoracic vertebral body,while the right bronchus was originated from the normal carina at the level of second and third thoracic vertebral body.The average angle of normal carina was about 59.2°,and the average angle of pseudocarina where BB originated from the left main bronchus was about 108.8°.The left main bronchus proximal to the origin of BB showed significant stenosis,with 1-2 mm width and 17 mm length in the involved segment.Six cases were type Ⅱ bridging bronchus,the right bronchus was absent in normal carina,BB originated at the level of fourth and fifth thoracic vertebral body,the average angle of pseudocarina was about 131°,the whole right lung was supplied by BB.The lower portion of trachea had stenosis in all 6 patients with 2-3 mm width and 30 mm length in the involved segment The lower portion of the trachea was found moving to the left in 4 patients and the left pulmonary artery sling was found in 2 patients.Conclusion MSCT can afford a definite diagnosis of BB by showing the morphology of trachea,bronchus,carina and relationship with surrounding organs with 3D reconstructions.