The azeotropy apparatus using the rectification method is used to determine the ternary azeotropic data for the benzene-n-heptane-ethanol system at 14.49, 21.18, 25.06, 40.69, 47.09 and 100.4 kPa. The dependence of ternary azeotrope on pressure is studied and correlated. The ternary azeotropes are predicted by Wilson activity coefficient model from the azeotropic data of the corresponding binary systems, and compared with the experimental data. A good agreement is obtained.