A critical analysis of the accuracy of the methods which predict vapour-liquid equilibria at elevated pressures. Four methods combining equations of state (EOS) and excess Gibbs free energy models are considered and their accuracies are compared with the precision of Soave-Redlich-Kwong (SRK) EOS using binary interaction coefficients k(ij) in the mixing rule. The analysis has defined the systems for which these four methods considerably improve the accuracy of the thermodynamic description as well as the mixtures for which the simple model SRK is more precise.