Dissolution profiles of ketoprofen (KPF) from solid dispersions in water-soluble polymers were investigated by the rotating disk method, and great differences in dissolution behavior were observed among different kinds of polymers. Therefore, the physicochemical nature of the polymers might play a predominant role in the dissolution of KPF from these solid dispersions. The quantitative relationship of dissolution behavior with several properties of the polymers depended on a combination of such factors as the water penetration of the compressed disk surface, pH of polymer solution and the apparent dissolution rate of polymers.