A water-soluble wheat pentosan polysaccharide has been observed in motion by atomic force microscopy (AFM). The motion occurred under aqueous buffer solution and has been attributed to the desorption and readsorption of segments of the molecule from the mica substrate on to which it had been physisorbed. The three classically described states postulated to be involved in polymer adsorption/desorption, namely loops, trains and tails were confirmed by direct observation. These observations validate long held, but largely untested, beliefs about the nature of the adsorption/desorption of polymer chains to surfaces.