A new model, based on statistical thermodynamic principles, has been developed for predicting the excess enthalpy of a ternary mixture from correlations of the enthalpies of its constituent binaries. The model provides a definite expression containing nine parameters. Since these are determined by analyses of the binary data alone, a real prediction of the ternary enthalpies is obtained. The model has been used to predict the excess enthalpies of 12 ternary systems involving a fairly wide variety of molecular species. The present treatment usually provides a better prediction of the ternary excess enthalpies than either the NRTL or the UNIQUAC models.