(Vapour + liquid) equilibrium data are presented for (methanol + ethyl tert-butyl ether) and (methanol + ethyl tert-butyl ether + toluene) at T = 328.15 K. The experimental results were measured by using a Boublik recirculation still. The binary results for (methanol + ethyl tert-butyl ether) and for the two other binary mixtures constituting the ternary mixture are well correlated by the Peng-Robinson equation of state modified by Stryjek and Vera with the modified Huron-Vidal first-order and Wong-Sandler mixing rules. The ternary experimental results are also reproduced with good accuracy by the equation of state.