Isobaric vapor-liquid equilibrium (VLE) data were measured for three ternary systems containing ionic liquids (ILs): water + 2-propanol + 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]), water + 1-propanol + [emim][BF4], and water + 1-propanol + 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The measurements were performed at P = 100 kPa and at several constant IL mass fractions. Activity coefficients of the volatile components were obtained without the need of a thermodynamic model of the liquid phase. The effect of the ILs on the relative volatility of the volatile components was depicted separately by their effect on the activity coefficients. Results of the activity coefficients showed that [emim](+) has a stronger interaction with water than [bmim](+); however, it has a weaker interaction with 1-propanol or 2-propanol. Boiling temperature data were also measured at 100 kPa for the six binary systems containing ILs. Ternary VLE data were also calculated from binary NRTL parameters, which were obtained from correlations of the binary boiling temperature data.