Vapour-liquid equilibria for the ternary system ethanol + tetrahydrofuran + cyclohexane and for the relevant binary mixtures have been determined at 298.15 K by head-space gas-chromatographic analysis of the vapour phase directly withdrawn from an equilibration apparatus. Experimental data have been described with different equations (Redlich-Kister, Wilson, NRTL and UNIQUAC) and excess Gibbs energies G(E) as well as activity coefficients gamma(i) of components have been obtained. All systems exhibit positive deviations. The binaries containing cyclohexane form azeotropic mixtures at 298.15 K, while ethanol + tetrahydrofuran and the ternary systems do not. The excess entropy and the temperature dependence of G(E) and gamma(i) have been calculated in the whole ternary domain from the known excess enthalpy and heat capacity.