AIM: To research the expressions of B-cell lymphoma gene 2(Bcl-2), Bcl-2 associated X-protein(Bax)and Ki67(proliferating cell marker)in the primary pterygium and normal bulbar conjunctiva, to explore the pathogenesis of pterygium.

METHODS: Thirty pterygium were surgically removed and 5 normal bulbar conjunctivas were also obtained. Formalin-fixed, paraffin-wax-embedded tissues were analyzed by immunohistochemistry with Bcl-2, Bax, Ki67.

RESULTS: The mean positive expression of Bcl-2, Bax and Ki67 in the primary pterygium was 14.73%, 7.00% and 12.73%, respectively 4.00%, 6.00% and 0 in normal conjunctiva group. The expression of Bcl-2 and Ki67 in the head of primary pterygium was higher than that of neck and body.

CONCLUSION: Bcl-2 and Ki67 have highly expressions in the primary pterygium, the expressions in the head of primary pterygium is the highest, the expressions in normal bulbar conjunctiva is low or no. There is no significant difference in the expression of Bax in the primary pterygium and normal bulbar conjunctiva. Apoptosis imbalance and abnormal proliferation of cells may be one of the mechanisms for the occurrence and development of the primary pterygium.