The effects of high pressure (up to 3600 kg/cm2) on the distribution coefficients of simple and complex anions have been studied on a strongly basic anion exchange resin. The retention volumes of Br−, Cl−, and NO2−were found to increase with pressure, and this was attributed primarily to an increase in the compression of the eluent, leading to greater volumetric flows at constant linear flows. The retention volume of the Pb(II) nitrate species was found to decrease significantly with pressure. This was attributed to a breakup of the anionic and neutral lead complexes to unretained cationic species and NO3−. The breakup occurred because of the greater ability of the more numerous dissociation products to decrease the volume of the system by electrostriction.