Objectives To examine expression of the connective tissue growth factor ( CTGF) gene in human thyroid cancer and establish whether a correlation exists between the presence of CTGF protein and clinicopathological parameters of the disease. Methods CTGF protein expression was investigated retrospectively by immunohistochemical analysis of CTGF protein levels in thyroid tumour tissue. Associations between immunohistochemical score and several clinicopathological parameters were examined. Results In total, 131 thyroid tissue specimens were included. High levels of CTGF protein were observed in papillary thyroid carcinoma tissue; benign thyroid tumour tissue scored negatively for CTGF protein. In papillary thyroid carcinoma, there was a significant relationship between high CTGF protein levels and Union for International Cancer Control disease stage III–IV, and presence of lymph node metastasis. In papillary thyroid carcinomas, CTGF protein levels were not significantly associated with sex or age. Conclusions These findings suggest that the CTGF protein level is increased in papillary thyroid carcinoma cells compared with benign thyroid tumours. CTGF expression might play a role in the development of malignant tumours in the thyroid.