Abstract: ObjectiveTo investigate prognostic factors for stage Ⅳa nasopharyngeal carcinoma. Methods From January 1, 2003 to December 12, 2004,145 patients with stage T4N0～3M0(UICC1997 staging criteria) nasopharyngeal carcinoma without prior treatment were recruited in this trial.The recurrence,metastasis,survival and prognostic factors were analyzed. Results 5-year overall survival (OS) rate,5-year cancer correlated survival (CCS) rate,5-year progression-free survival PFS) rate,5-year disease locoregional recurrence-free survival (DLRFS) rate and 5-year distant metastasis-free survival (DMFS) rate was 59.2%,61.3%,53.0%,71.6% and 62.6%,respectively.Multivariate analysis showed: carotid sheath invasion was a poor prognostic factor affecting LRFS and DMFS,UICC N staging was an independent prognostic factor affecting LRFS and DMFS; carotid sheath invasion was an independent poor prognostic factor affecting CCS,age,neck exposure dose and UICC N staging were independent prognostic factors affecting CCS.Univariate analysis showed: carotid sheath invasion and UICC N staging were prognostic factors affecting CCS and PFS,although concurrent chemotherapy or radiotherapy in combination with chemotherapy resulted in the trend of improving DMFS and CCS,there was no statistically significant difference (P>0.05). Conclusion Carotid sheath invasion and UICC N staging were important prognostic factors for stage T4 non-metastatic nasopharyngeal carcinoma.