In this study, hydrogels were prepared from blends of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP). The miscibility of the polymers was confirmed with differential scanning calorimetry with the appearance of a single glass-transition temperature. Additionally, a negative Flory-Huggins interaction parameter further verified the interaction between PVA and PVP. We evaluated the stability of the hydrogels by swelling the gels in phosphate-buffered saline solutions at pH 7.4. With attenuated total reflectance-Fourier transform infrared spectroscopy, it was determined that, during swelling, PVP dissolved out of the gel over time and the equilibrium gel content of PVP was nearly identical in all of the samples investigated. After the dissolution of PVP, the equilibrium water content of the gels ranged from 64 to 76 wt% Additionally, rubber elasticity studies were performed to elucidate information about the physically crosslinked network Structure. As determined from rubber elasticity experiments, the mesh size of the physically crosslinked hydrogels ranged from 90 to 230 A. (c) 2009 Wiley, Periodicals, Inc. J Appl Polym Sci 112: 541-549, 2009