Objective: To describe the relation between the degree of positivity of the immunohistochemical staining of P53 expressed within the studied biopsies and the malignant tendency in cases of sinonasal inverted papilloma. Study Design: Study design included studying of the histopathological findings of 28 biopsies of lesions proved to be inverted papilloma and application of the immunohistochemical staining of P53 , then corrolational study between the positivity of the staining of P53 and those histopathological findings was done to study its relation with recurrence and malignant transformation. Methods: This retrospective study included 28 cases of proved inverted papilloma, 18 males and 10 females, their biopsies were studied histopathologically and stained immunohistochemically for P53. Charts were reviewed and tabulated for lesion pattern, epithelial type, dysplastic changes, recurrence and malignant changes. Results: There is a direct relation between the grade of dysplasia of the lesion and its pattern with the grade of strength of the immunohistochemical reaction. The rates of recurrence and malignant transformation are clearly related to the degree of positivity of the immunohistochemical staining for P53.