OBJECTIVE To investigate the significance of vascular endothelial growth factor (VEGF) and nuclear factor-kappaB (NF-κB) expression in thyroid carcinoma.METHODS The expression of NF-κB and VEGF was determined by immunohistochemistry in formalin-fixed and paraffin-embedded specimens obtained from 10 normal thyroid tissues (NT), 12 cases of thyroid adenoma (TA) and 68 cases of thyroid carcinoma (TC).Differences in expression between NT, TA and TC were statistically analyzed. In addition, in cases of TC, the relationship of NF-κB and VEGF expression with various clinicopathological factors, including histological typing, clinical staging and lymph node metastasis, as well as the correlation between NF-κB and VEGF expression was examined.RESULTS In contrast to the negative immunoreactivity for VEGF in NT,there was a significantly higher positive incidence (PI) in TA (41.7%, P=0.040) and TC (75.0%, P＜0.001), and a significant difference between TA and TC (P=0.036). Immunoreactivity for NF-κB in NT was negative and significantly higher in TC (63.2%, P＜0.001),but not in TA (16.7%, P=0.481). However the PI difference between TA and TC (P=0.003) was significant. Between the histological types of TC, a significantly higher PI was found in undifferentiated thyroid carcinoma (UTC),namely, 100% for VEGF and 90.0% for NF-κB. We also found significant positive relationships of VEGF and NF-κB expression with the clinical stage and lymph node metastasis. Furthermore, a significant positive correlation between VEGF and NF-κB expression in TC was observed.CONCLUSION Our data showed that the expression of VEGF and NFκB/P65 was greater in TC and UTC, and documented their significant positive correlations with the clinical stage and lymph node metastasis in TC. In addition there was a significant positive relationship between their expression, suggesting that they have important roles in TC and that they may be potential targets for gene therapy in TC patients.