8-Anilino-1-naphthalenesulfonic acid was used as fluorescent probe to detect the presence of hydrophobic sites in aqueous solutions of copolymers of acrylamide andN-alkyl-acrylamides. 8-Anilino-1-naphthalenesulfonic acid ammonium salt hydrate (ANS) was employed as guest molecule to investigate the temperature dependence of affinity behavior of β-cyclodextrin-incorporated poly(N-isopropylacrylamide) hydrogels with ANS.