Abstract: Objective: To investigate the expression of Bcl-2 and CD34 in the head，neck and body part of the primary pterygium， and to explore the pathogenesis of pterygium. Methods: The expressions of Bcl-2 and CD34 in 30 specimens from patients with primary pterygium and 5 specimens of normal bulbar conjunctiva were detected by immunohistochemical staining ( EliVision method) ， their correlation was analyzed statistically. Results: The expression of Bcl-2 and CD34 in the head，neck and body part of the pterygium had statistically significant differences( P ＜ 0. 01) . The expression of Bcl-2 and CD34 was higher in the head part than that in the neck and body part of the pterygium( P ＜ 0. 01) ; the expression of CD34 in the neck part was significantly higher than that in the body part( P ＜0. 01) . Conclusions: Bcl-2 and CD34 express high in the head，neck and body part of the pterygium，and express the highest in the head part. It suggests that the head part of the pterygium has less apoptosis than the other parts; but it is more proliferative and has the probability of excessive repair，which may the pathogenesis of the pterygium.