Excess molar volumes (V-E) and deviations in molar refractions (Delta R) and the isentropic compressibility (Delta kappa(s)) were determined for the systems ethanol + methanol + 2-methoxy-2-methylpropane and ethanol + methanol + 2-methoxy-2-methylbutane at 298.15 K and atmospheric pressure. For both systems, these results were satisfactorily correlated by the Redlich-Kister polynomial. Several empirical equations allowing prediction of the results for the ternary systems from the V-E, Delta R, and Delta kappa(s) of their constituent binary subsystems were also examined. The Kohler equation gives the best predictions of VE, while the equations of Radojkovic et al. and of Jacob and Fitzner give the best predictions of Delta R and Delta kappa(s).