We present four cases of internal carotid artery (ICA) transposition which caused widening of the retropharyngeal soft tissues. Internal carotid artery transposition is a rare cause of retropharyngeal space enlargement, which can be accurately diagnosed in a non-invasive manner with spiral CT. Radiologists should be aware of this entity in the differential diagnosis of retropharyngeal space enlargement in symptomatic (dysphagia, pulsatile mass) and asymptomatic patients, and alert the clinician of its existence, due to the risk of massive bleeding if neck surgery is to be performed.