Drug release kinetics from different types of hydrogels at 37°C has been studied in our laboratory. The hydrogel families used are poly(acrylic acid-co- acrylamide), poly(acrylic acid-co-methyl methacrylate) and poly(N-isopropylacrylamide-co-itaconic acid) and the drugs are theophylline, aminophylline and nafcilline. Drug release from swollen hydrogels is fickian, but deviates from it in the case of nafcilline release from acrylic acid/methyl methacrylate. The release from xerogels is non-fickian. Diffusion coefficients as a function of concentration of N,N’- methylenebisacrylamide and results on the effects of crosslinking density on the release of theophylline are reported.