Ternary excess molar enthalpies for (methanol + ethanol + methyl tert-butyl ether (MTBE)) and methanol +, 1-propanol + MTBE) mixtures have been measured with a flow microcalorimeter at T = 298.15 K and atmospheric pressure. Constant contours for the ternary experimental results were calculated by a polynomial equation. Further, the results have been compared with those calculated from a UNIQUAC associated-solution model taking into account the molecular self- and cross-association of two alcohols and the solvation among the alcohols and MTBE. The results predicted by using binary parameters obtained from the corresponding experimental binary results alone are in good agreement with the experimental values.