Headspace gas chromatography (HSGC) is a relatively new and promising technique to study the vapour-liquid equilibrium (VLE) of mixtures. It is simple, accurate, and fast. The VLE of 1-propanol-water mixtures was studied at 60 degrees C in the absence and in the presence of 3 Angstrom and 4 Angstrom molecular sieves using the HSGC technique. The results obtained showed that the VLE of 1-propanol-water mixtures was altered significantly in the presence of molecular sieves and the azeotropic point of the system, at about 40 mol% 1-propanol in the normal case, was eliminated in the presence of the molecular sieves.