The letter underlines the need for a reflection and a debate on the quantitative results arising from the application of current theories on the calculation of acid-base properties of polymer surfaces from wetting measurements, To this end, published results on the Lewis acid-base properties of poly(methylmethacrylate) (PMMA) and of poly(vinylchloride) (PVC), as evaluated by the application of the Fowkes (work of adhesion; Fowkes, F. M., in "Surface and Interfacial Aspects of Biomedical Polymers" (J. D. Andrade, Ed.), Vol. 1 Chap, 9. Plenum Press, New York, 1985) and Good-Van Oss-Chaudury (electron donor-electron acceptor components; Good, J. R., and van Oss, C. J., in "Modern Approach to Wettability : Theory and Application" (M. E. Schrader and G, Leed, Eds,), Chap, 1, Plenum Press, New York, 1991) approaches to interfacial energetics, are compared, The former approach indicates the basic character of PMMA and the acidic nature of PVC surfaces. When the components of the solid surface free energy are calculated according to the Good-Van Oss-Chaudury theory, both surfaces appear overwhelmingly basic, PMMA being a stronger base than PVC, Data are compared to published results on the acid-base nature of PMMA and PVC, as evaluated by experiments not based on wetting measurements, The need for a more complete understanding of the quantitative aspects of the wetting-measurement-based approaches to Lewis acid-base interfacial interactions is stressed.