The sorption isotherms of peanuts at 25 degreesC were determined gravimetrically, in the range of water activity (a,) 0.577-0.903. The most common peanut varieties in Argentina (Flour Rummer, Tobaldo, Colorado and Roata), were used with 47.2%, 43.9%, 47.6% and 50.9% (dry basis) of oil content respectively. To check if there is any difference among varieties, the statistical methodology used with the transformed data allows comparison of the adsorption isotherms of peanut varieties as a whole. The four peanut varieties show significant differences in moisture sorption even if moisture content is expressed in an oil-free basis. (C) 2000 Elsevier Science Ltd. All rights reserved.