The effect of the presence of 3 and 4 Angstrom molecular sieves on the vapor-liquid equilibrium (VLE) of the ethanol-water system was investigated using the headspace gas chromatography (HSGC) technique. The VLE of the system was considerably altered in the presence of molecular sieves and the azeotropic point was eliminated. Attractively, in the presence of molecular sieves, pure ethanol was obtained from a feed composition of 40 mol.% ethanol. The separation efficiency was a function of the weight and pore size of molecular sieves. Moreover, results obtained add to the validity of using the HSGC apparatus in studying the VLE in various systems.