['Pterygium is the fibrovascular growth of the limbal conjunctiva over cornea. This proliferative nature might have a pathogenesis associated with tight junction proteins.', 'To investigate the tight junction protein claudin-1 expressions in pterygium with respect to normal conjunctiva.', 'This retrospective study included 28 patients who underwent pterygium surgery with autograft. Claudin-1 expressions were immunohistochemically evaluated in normal and lesional conjunctiva of the same eye. Immunohistochemical evaluation was done with regard of both the intensity and the extent of staining. The distribution of the immunohistochemical scores in pterygium and normal conjunctiva has been compared with using McNemar test.', 'The mean age of the patients was 52.2\u2009±\u200911.2 years and male/female ratio was 8/20. Among 28 samples of normal conjunctiva 25 (89.2%) demonstrated a strong immunohistochemical expression with claudin-1 whereas this rate was 10.8% for pterygium samples. Statistical analysis revealed a significant decrease in claudin-1 expressions in pterygium with respect to normal conjunctiva (p\u2009<\u20090.001).'] Do claudin-1 expressions decrease in pterygium with respect to normal conjunctiva?