Papillary thyroid carcinoma frequently metastasizes to regional lymph nodes, and lymph node metastasis increases the risk of local regional relapse. Recent evidence suggests that vascular endothelial growth factor-D (VEGF-D) promotes lymphangiogenesis, which in turn promotes lymphatic metastasis. Therefore, the role of VEGF-D messenger RNA transcript levels and VEGF-D immunoreactivity in lymph node metastasis in papillary thyroid carcinoma was investigated. In addition, the role of blood vascular vessel, lymph vessel, and Flt-4-positive vessel densities were studied in relation to their suspected association with lymph node metastasis, and with VEGF-D expression. VEGF-D messenger RNA transcript levels by quantitative real-time reverse transcription-polymerase chain reaction and VEGF-D immunoreactivity by immunohistochemistry in 49 papillary thyroid carcinomas were also studied. This was followed by quantitative immunohistochemical staining for CD34, podoplanin, and Flt-4. Lymph node metastasis was significantly correlated with VEGF-D messenger RNA transcript levels (P=0.027) and VEGF-D immunoreactivity (P=0.019). Increased lymph vessel density was also correlated with VEGF-D expression and lymph node metastasis. In conclusion, our findings indicate that VEGF-D expression and increased lymph vessel density may have an important role for lymph node metastasis in papillary thyroid carcinoma.