PURPOSE: To describe the dural tail sign in contrast-enhanced MR images of nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: MR images of 19 consecutive patients, in whom three years previously squamous cell type NPC had been pathologically proven, were reviewed for the presence or absence, location and direction of the dural tail sign and the relationship between this sign and the skull base invasion. Histopathologic specimens obtained in two patients were also described. RESULTS: In ten patients (53%), there was bony invasion of the skull base; in seven of these (37%), dural tails were found. In seven, this tail extended along the floor of the middle cranial fossa; in 5, along the petro-clivus, and in 4, along the tentorium. In all these cases, the adjacent skull base was involved. Histopathologic examination in two patients with dural tails in the middle cranial fossa revealed fibrosis and hyper-vascularity of the dura mater without evidence of tumor cell infiltration. CONCLUSION: The dural tail sign appears to be not infrequent in patients with advanced NPC. The dural tail may be a good indicator of intracranial tumor spread.