Experimental data on liquid-liquid equilibrium for the ternary systems acetic acid – n-amyl alcohol – water, acetic acid – n-amyl acetate – water, n-amyl alcohol – n-amyl acetate – water and for the quaternary system acetic acid – n-amyl alcohol – n-amyl acetate – water at 293.15 K, 303.15 K, 313.15 K and 323.15 K and atmospheric pressure were obtained by gas chromatography method. Phase diagrams are presented using Gibbs composition triangle and composition tetrahedron. Sufficient agreement of experimental tie-lines with calculated by NRTL model is observed: standard deviation does not exceed 1.2%.