The determination of vapor pressures, p0, of compounds with low vapor pressures (10(-8) Pa < p0 < 10(3) Pa) is becoming increasingly important as a result of the need to measure p0 for environmentally sensitive compounds such as organophosphorus pesticides, biphenyls, dioxins and alkylbenzenes. Under strict conditions, the components of gas-liquid chromatography (GLC) (a volatile solute, an involatile solvent and a mobile carrier gas) are in equilibrium and as a result it is possible to use the technique to measure equilibrium properties such as vapor pressure. The technique is rapid, reliable and reproducible. These advantages have tempted many workers to measure physiochemical properties, including vapor pressures, under conditions for which the basic theories do not hold. In this review, the GLC techniques used to measure vapor pressures from GLC data together with the basic theory, limitations of the techniques and some recent measurements are discussed.