Abstract： AIM: To study the expression of hypoxia-inducible factor ( HIF ) and Pax6 in pterygium and investigate the relationship between expression of HIF and Pax6 in pterygium. <br> METHODS:Thirty-five patients with pterygium who underwent simple excision and 10 cases of normal conjunctival tissues were enrolled in this study. Immunofluorescence was performed in pterygia tissue and normal conjunctiva, detecting the expression of HIF-1α and Pax6. <br> RESULTS:The positive expression rate of HIF-1α was 66% ( 23/35 ) and 10% ( 1/10 ) in pterygia tissue and normal conjunctiva, respectively. The difference of expression between pterygia tissue and normal conjunctiva was statistically significant (P<0. 05). Expression of Pax6 was full-thickness nuclear in normal conjunctiva;however, expression of Pax6 decreased and even was negative in pterygium. The difference of expression in two groups was statistically significant (P<0. 05). <br> CONCLUSION: HIF - 1α is highly expressed in pterygium, suggesting that it may be involved in the occurrence and development of pterygium. Pax6 gene downregulated in pterygium epithelial cells, suggesting that epithelial cells are squamous metaplasia.