Escobedo and Mansoori (1996) recently proposed a new expression, originally derived from statistical mechanics, for the surface-tension prediction of pure fluids. The theory presented here is extended to mixtures of organic liquids based on the conformal solution theory of mixtures. Using the proposed equation, surface tensions of 55 binary mixtures are predicted within an over-all 0.50 AAD%, which is better than other available prediction methods. The 55 binary mixtures are predicted within an overall 2.10 AAD% with a corresponding-states version of the theory. The expressions proposed in this work are general since they have been applied to a variety of binary mixtures, and the results obtained agree well with the experimental data. The proposed model is directly applicable to multicomponent liquid mixtures.