The adsorption of a number of polyaromatic hydrocarbons onto aqueous colloidal kaolin was studied. The fluorescence polarization and hence the fluorescence anistropy of the hydrocarbons was measured as a function of their concentrations in aqueous solutions containing the colloid. The fluorescence anisotropy was found to be highest for dilute solutions of polyaromatic hydrocarbons, with often sharp decreases at higher concentrations. More concentrated solutions gave an isotropies similar to those of plain aqueous solutions of the fluorophores. The concentrationversusfluorescence anisotropy curves and BET surface area data were used to calculate surface coverage of the colloid by the adsorbed hydrocarbons. Coverage in the range of 1% to 14% of the colloid surface was found at surface saturation for the compounds studied. This suggested that colloidal clays have the potential of transporting polyaromatic hydrocarbons through environmental waters.