Pterygium is a wedge-shaped fibrovascular growth of conjunctiva that extends onto the cornea. The etiopathogenesis of pterygium is still not fully elucidated. Exposure to ultraviolet light is suggested as one of the most important factors contributing to pterygium development. However, other factors including allergens, harmful chemical substances, wind, dust and pollens also may contribute to its development. The aim of the study was to evaluate the influence of immune reactions on the pathogenesis of pterygium.