This paper reports on the surface tension of the binary mixtures {propyl propanoate+o-xylene}, {propyl propanoate+m-xylene} and {propyl propanoate+p-xylene} at the temperature 298.15 K and atmospheric pressure, over the whole composition range. The surface tension deviations obtained were correlated with a Redlich-Kister type equation. These data were compared with five different theoretical approaches. Among them we apply the theories of Hildebrand and Scott for ideal solutions and their extension of Guggenheim's ideal solution equation, valid for systems containing molecules of significantly different size; the Brock and Bird theory, based only in the critical values of the pure compounds; the Sudgen's equation based in the parachor, which needs the knowledge of density for the whole composition in the mixture; and finally, the Prigogine's refined theory, which takes into account the critical values and the temperature dependence of surface tension. We will discuss results from those five theoretical models applied to the experimental data presented in this work, and also to other previously published data. Also, we will discuss the influence of the surface molar area parameter value on the models that need it. (c) 2005 Elsevier B.V All rights reserved.