The liquid-liquid equilibria (LLE) of three ternary systems formed by toluene, heptane, and 1-alkyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids {[xdmim][Tf(2)N], where x refers to ethyl (e), propyl (p), or butyl (b)} were determined at T = 313.2 K and atmospheric pressure. The methyl group in position 2 in the imidazolium cation seems to improve the selectivity of the liquid-liquid extraction process of toluene from heptane compared to the results previously obtained for 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids {[xmim][Tf(2)N], where x refers to ethyl (e), propyl (P), or butyl (b)). [edmim][Tf(2)N] and [pdmim][Tf(2)N] ILs seem to be alternatives for sulfolane in the extraction of toluene from heptane. The experimental LLE data were satisfactorily correlated by means of the thermodynamic nonrandom two-liquid (NRTL) model.