New fluid phase equilibria data containing ETBE as an ether synthesized from ethanol of biological origin are presented giving isothermal p-x-y data for the ternary system ethyl 1,1-dimethylethyl ether (ETBE)+ n-heptane + toluene and the three binary systems involved at 313.15 K. A static technique consisting of an isothermal total pressure cell was used for the measurements. Data reduction by Barker's method provides correlations for G(E), using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL, and UNIQUAC models have also been applied to both binary and ternary systems. The mixtures measured exhibit slight positive deviation from ideal behavior.