Gasket materials, whether manufactured by the beater addition or the compressed sheet process, are inherently porous composites. The quantity and morphology of the pores existing in the structure will depend on the manufacturing specifics, the formulation and other variables. Since the primary function of the gasket is to prevent the flow of fluid, having an understanding of the type and nature of its pore structure aids in the tailoring of a material for a specific application as well as making formulation changes which will further enhance performance. Furthermore, knowledge of the pore structure as it exists in the actual flange environment should provide additional insight into gasket performance. The purpose of this paper is to discuss how pore structure of gasket materials influence their performance.