A method for testing the thermodynamic consistency of binary and isothermal vapor-liquid equilibrium data at moderate and high pressures is proposed, using a phi-phi approach. The Redlich-Kwong-Soave equation of state with Huron-Vidal mixing rules at infinite pressure is used in the data-reduction procedure, and a Margules equation is used to calculate the activity coefficients at infinite pressure. This model is shown to be themodynamically consistent. The proposed method allows us to check consistency of vapor-liquid equilibrium data in the presence of components at the gaseous and supercritical states.