Background: Pterygium is one of the most commonly occurring eye diseases. It is widely regarded as a degenerative condition. Pterygium shares some similarities with tumors, as active cell proliferation.. P63, a member of the p53 gene family is a transcription factor that is crucial for the development and maintenance of stem cells in stratified epithelia. It is present in the limbus and sustains the proliferative potential of limbal stem cells. This study aims to evaluate the pattern of p63 expression in cases of pterygia, and to correlate this pattern with their clinicopathological parameters.Materials and methods:p63 immunostaining was studied in 52 specimens of nasal pterygia using avidin-biotin peroxidase method.Results: p63 was expressed in 61.5% of cases withvariation in its expression, strong 25%, moderate 21.1%, and mild in 15.4% of cases. There was significant increase in p63 expression in recurrent pterygia than in primary (p<0.03).Conclusion: Pterygium is a disease of limbal stem cells as reinforces ofP63 gene in the pathogenesis of pterygium could explain the triangular shape of pterygium and the high amount of recurrence.Keywords: Pterygium, p63, stem cells.Abbreviation: Transiantamplyfing cells (TACs), Limbal epithelial stem cells (LESCs), Fuchs flecks (FF), Conjunctival intraepithelial neoplasia (CIN)