High-molecular-weight atactic poly(vinyl alcohol) (a-PVA) gels loaded with (R,S)-2-(3-benzoylphenyl)propionic acid (ketoprofen) were prepared from 5, 6, 7, and 8 g/dL solutions of a-PVA with a number-average degree of polymerization of 4000 in an ethylene glycol/ water mixture with an aging method to identify the effect of the initial polymer concentration on the swelling behavior, morphology, and thermal properties of a-PVA gels. Then, the release behavior of ketoprofen from a-PVA gels was investigated. As the polymer concentration decreased, the ability for network formation decreased, and the degree of swelling of the a-PVA gels increased. In addition, the enthalpy increased with an increase in the a-PVA concentration, but the melting temperatures of the gels prepared at different initial polymer concentrations were the same; this indicated that tighter gel networks would be formed by a higher polymer chain density. (c) 2007 Wiley Periodicals, Inc.