Excess molar volumes V-m(E) at the temperatures 288.15 K, 298.15 K and 308.15 K and normal atmospheric pressure of binary mixtures of tetrahydrofuran or tetrahydropyran with cyclohexane or toluene have been computed from density measurements. From the results, the thermal expansion coefficients, alpha, were estimated. The Prigogine-Flory-Patterson theory and its applicability in predicting V-m(E) is tested.