The applicability of the Antoine equation to the indirect determination of vaporization heat by the Clausius-Clapeyron equation was studied. A correlation was proposed for the difference of compressibility factors for saturated liquid and gas phases, Dz, at pressures up to 101.325 kPa, which does not require the knowledge of critical properties. The difference Dz makes it possible to take into account the influence of the real behaviour of liquid and gas phases on the vaporization heat. The proposed correlation was successfully verified on published data for water, hexane and cyclohexane. The standard deviation of the calculated and published values of vaporization heat decreased when using the proposed correlation by 50-75 % in comparison with the values calculated without the correction Dz.