The (liquid + liquid) equilibria for {x(1)CH(3)CN + x(2)C(6)H(5)NH(2) + (1 - x(1) - x(2))CH3(CH2)CH3}, {x(1)CH(3)CN + x(2)C(6)H(5)NH(2) + x(3)CH(3)(CH2)(5)CH3 + (1 - x(1) - x(2) - x(3))C6H6}, and {x(1)CH(3)CN + x(2)C(6)H(5)NH(2) + x(3)CH(3)(CH2)(5)CH3 + (1 - x(1) - x(2) - x(3))CH3OH} at the temperature 298.15 K have been measured. The experimental results were well correlated with extended UNIQUAC and modified Wilson models with binary, ternary, and quaternary parameters.