The polyacrylamide hydrogel (PAAG) Aquamid® (Contura International A/S Soeborg, Denmark) is one of the new macromolecules that are used as implants and tissue fillers in reconstruction and aesthetic surgery. This study showed, by means of radioactive isotope methods, that PAAG can exchange both physiological and non-physiological constituents very efficiently with the surrounding medium. The efflux (J, mole/(cm(2) ¿×¿s), 25¿°C, pH 7.2) of water (4.4¿×¿10(-5) ), chloride (2.4¿×¿10(-7) ), urea (1.0¿×¿10(-9) ), and glucose (1.1¿×¿10(-9) ) was 3-40x greater than in human red blood cells. PAAG was also accessible to sucrose, inulin, and benzylpenicillin that could not permeate biological cell membranes. The conclusion of the study is that the hydrogel structure created no significant barrier to the exchange of solvent and solutes with the surrounding medium. Copyright © 2011 John Wiley & Sons, Ltd.