Four commercially available cavity liners were evaluated as to their permeability characteristics. The contact angle measurement of each liner also was calculated. S. S. White liner was found to have the lowest contact angle and permeability values with a better wetting property. Copalite, on the other hand, was found to have the highest contact angle and permeability values with a poor wetting property. Caulk varnish and Polyvar had values lying between the two materials. Copalite is the preferred material in decreasing marginal leakage because of its high contact angle, whereas the S. S. White liner is preferred in pulpal and axial surface protection because of its good wetting properties.