Abstract: Objective : To analyse the likelihood of early detection for cavernous sinus invasionCSI in nasopharyngeal carcinoma NPC. Methods : From March 1998 to December 2001, the clinical records of 59 patients of NPC who detected CSI by CT or MR were retrospectively studied. Among them, 47 cases were newly diagnosed disease, 12 recurrenced disease. Analyses of the relationship between headache /skull base invasion/cranial nerve palsy and CSI were presented. Results : Headache occurred as an initial symptom in 78.0% (46/59), and mostly localized in same unilateral position in CSI(84.8%). The cranial nerves (V、VI)、 the bone of the skull base both were simultaneously affected in approximately 70% patients having headache. Invasion of the bones of the skull base was present in about 90% of CSI cases,and the most common sites of bone destruction were sphenoidal body(77.4%)、 lacerate foramen(64.2%) 、basiler clivus(54.7%), and 66.0% of these cases had over three sites of extensive bone infitration as "windowing". In our series of SCI, 47 cases showed lesions of cranial nerves, most frequent involvement for abducent nerve (38/47), and the special feature of co-existing lesion among the cranial nerves II、III、IV、V1、V2、 V3 and VI. The symptom of visual blurring was found in 26 cases with CSI (44.1%). Among these cases, the symptom appeared earlier than the nerve lesion for 4 cases, and 2 without nerve sign. Conclusions : Our findings indicate that the primary tumor directly infiltrate upward through extended area of the bone destruction into cavernous sinus.Headache、cranial nerve palsy and visual blurring are major symptoms caused by CSI, and the latter may be presented as initial complaint in partial patients with CSI in NPC.