The isothermal vapor-liquid equilibria of diethyl carbonate (DEC) + isooctane/n-heptane/toluene systems were measured using a simple quasi-static ebulliometer at temperatures ranging from 303.15 to 323.15 K The validity of the experimental apparatus was checked by comparing the measured vapor pressure of pure DEC, isooctane, n-heptane, and toluene with the published data and obtaining average absolute deviations less than 1.2%. The experimental data were correlated using the Wilson, nonrandom two-liquid, and universal quasichemical models with average absolute deviations in vapor pressure between calculated values and experimental data of 1.0%, 1.0%, 1.0% respectively, for isooctane + DEC system; 0.9%, 0.9%, 0.9%, respectively, for n-heptane + DEC system; and 1.0%, 1.1%, 1.1%, respectively, for toluene + DEC system. The experimental vapor pressure data for all systems show strongly nonideal solution with positive deviation from Raoult's law. The systems studied show that no azeotropic point is exhibited by the systems.