The sulfonated cotton fabrics (sulfur content: 0–0.52%), obtained by the treatment with propane sultone, were subjected to graft copolymerization with acrylonitrile. The values of the % graft of the sulfonated cotton fabrics were higher than those of untreated cotton fabrics. The sulfur contents of the sulfonated cotton fabrics, however, affected little the % graft. The sulfonated and grafted cotton fabrics absorbed basic dyes, Methylene Blue, Diamond Green, and Cathilon Red. The color fastness of these dyes towards light from a Xenon lamp and towards ultraviolet radiation was significantly improved by the introduction of polyacrylonitrile onto cotton.