Bindings of some anionic dyes containing sulfonyl group(s), namely, Acid Blue 74 (AB-74), Acid Orange 7 (AO-7), Acid Green I (AG-1), Direct Blue 53 (DB-53), and Calconcarbosylic acid (CCA) onto crosslinked poly(N-vinylpyrrolidone) (CPVP) have been investigated using adsorption isotherm parameter. The dyes were linked positively charged on the tertiary nitrogen atom on the pyrrolidone ring in polymer chain resulting keto-enol tautomerism from sulfonyl group on the benzene ring in the dyes molecules. In the experiments of adsorption, I, (Langmuir) type adsorption in the Giles classification system was found. Monolayer coverages (n) of polymer/dye system were founds by "B point" methods. Adsorption studies indicated that monolayer coverages of CPVP by the anionic dyes containing sulfonyl group(s) were increased with following order; CCA > AG-1 >> DB-53 > AO-7 > AB-74.