Background: Epithelial carcinogenesis is associated with loss of tissue architecture characterized by loss of organized cell–cell and cell–matrix adhesions, allowing the migration of malignant cells. The histological grade of carcinomas is a significant prognostic parameter and depends on the differentiated degree of glandular epithelium and cellular polarity. One of the key determiners controlling cellular adhesion and polarity is the Tight Junctions, The purpose of the present study is to assess changes of claudin-1expression among different grades of salivary gland carcinomas. On the other hand comparing its expression with Matrix metallaoproteinase-9 in the same lesions and find out if there is a possible correlation between them. Methods: A total of sixty one of salivary glands carcinomas were immunostained with polyclonal antibody for claudin-1 and matrix metalloproteinase Results: revealed downregulation of claudin-1 in high grade tumors in different malignant neoplasms of salivary glands, except in squamous cell carcinoma where it is upregulated in poorly differentiated tumors while There was an increase in the positive immunoexpression of Matrix metallaoproteinase-9 from low to medium till it reaches its maximum expression in high grades. Conclusion: claudin-1 and Matrix metallaoproteinase-9 in majority of lesions using Paired Student's t-Test revealed a highly significant statistical difference, Further investigations are required for the determination of the role of claudin-1in salivary gland carcinogenesis and invasion. This may add valuable information and ncrease our understanding of Tight Junctions which may provide us with more practical implications in anticancer therapy