AIM: To investigate the expression of different kinds of transforming growth factors beta- 1(TGF- β1)and changes of activin receptor-like kinase(ALK)in pterygium and normal conjunctiva tissues. METHODS: A total of 40 cases(40 eyes)of pterygium patients who underwent surgical treatment in our hospital were selected. In the same period, 40 cases(40 eyes)of normal conjunctiva tissues removed from the eye due to cataract surgery were selected. The expression of TGF-β1 receptors(ALK1/ALK5)in pterygium and normal conjunctiva tissues was detected by immunohistochemistry, with the proportion of positive staining cells counted. The expression of ALK1 and ALK5 mRNA and their proteins were quantified by reverse transcription polymerase chain reaction(RT-PCR)and Western Blot, respectively.RESULTS: According to immunohistochemistry results, the ALK1 expression level was increased more distinct in pterygium group, compared to the normal conjunctiva group, and it was detected throughout the full-thickness pterygium epithelial cells, while only in the basal layer of epithelial cells in normal conjunctiva tissues; the ALK5 was detected in the basal layer of epithelial cells in both groups, while its level was decreased in the pterygium group compared to normal conjunctiva group. There was significant difference in the proportion of ALK1 and ALK5 positive cells between the two groups(all P<0.05). The expression of the ALK1 mRNA and its protein in the pterygium tissues were significantly elevated, while the ALK5 mRNA level and its protein was significantly decreased, compared with the normal conjunctival group(P<0.05).CONCLUSION: Compared with the normal conjunctiva tissues, the expression of ALK1 and ALK5 in pterygium tissues was increased and decreased, respectively. This indicated different activation status of TGF-β signaling pathway, providing experimental evidence for further study on the pathogenesis of pterygium.