The swelling behaviors of poly(acrylamide) (PAAm)/clay nanocomposite hydrogels (hereinafter abbreviated as NC eels) in acrylamide (AAm) aqueous solution have been investigated. As-prepared PAAm/clay hydrogels (S-M gels) were posttreated by immersing them in AAm aqueous solution. It was found that the swelling ratio of the NC gels increased greatly when the concentration of the Solution is below a critical concentration (c*), whereas the gels were disintegrated in the Solution when the concentration of the Solution is above the c*. Some disc-like particles were found in the AAm Solution accompanying With the unusual swelling behaviors. This unusual swelling behavior is resulted from the change of network structure of the NC gels in AAm aqueous solution, which was further convinced by transmission electron microscopy and element analyses. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 112: 353-358, 2009