Abstract: Objective: To compare the diversity in tumor extension of nasopharyngeal carcinoma (NPC) by computerized tomography (CT) versus magnetic resonance imaging (MRI) and to evaluate the impact on '92 staging system by using M R imaging. Methods: A total of 250 cases with NPC,histologically diagnosed, received enhanced spiral CT and MRI scans of nasopharyngeal and cervical region were enrolled in this study. Clinical staging was scored according to '92 staging system based on both of CT or MRI data and clinical information. Results: MRI was significantly superior to CT in the detecting of invasion of extra-nasopharyngeal cavity, anterior-styloid space, oropharynx, retropharyngeal lymphatic metastasis, base of skull, cavernous sinus, nasal sinuses, cervical vertebra, and infratemporal fossa. There was no statistical difference between CT and MRI in the evaluation of involvement of nasal cavity, post-styloid space, and cervical lymph node metastasis. According to MRI data, 32.0 % of T classification, 11.6% of N classification, and 30.0% of clinical stage were shifted. Conclusion: There is remarkable advantage of MRI in the detection of infiltration of extra- nasopharynx cavity, base of skull,nasal sinuses, cavernous sinus, and retropharyngeal lymphatic metastasis of NPC. The result of MRI is identical with that of CT in metastasis of cervical lymph node. MRI mainly influences on T classification, and shows little impact on N classification of '92 stage system. The change of clinical stage will benefit the adjustment of treatment strategy for NPC.