A knowledge of the aqueous solubility of crude oils is important in the assessment of the environmental effects of oil spills. The applicaton of the gas stripping method to the determination of the aqueous solubility of weathered crude oils is described here and some environmental implications discussed. It is suggested that gas stripping is the best method of determining the aqueous solubility of the lighter components of crude oils. The environmental implications are that aquatic biota may be exposed to relatively high concentrations of dissolved aromatic hydrocarbons in the first hours after a crude oil spill but as the oil weathers its solubility, and presumably the toxic effects, are reduced.