In order to investigate the effect of chlorine and chlorine/ultraviolet ray on the color fastness of nylon swimming wear, nylon fabrics dyed with two acid dyes were treated with an aqueous sodium hypochlorite solution varying the concentration and pH. Oxidation potential of the solution increases with decrease of pH. Although the dyes in the solution faded in the same order with increase of oxidation potential of sodium hypochlorite, the dyes on the fabrics faded to a greater degree at pH 7 than at pH 5. In view of the result achieved, it seem that internal structure of the fiber greatly affects to the fading of dyeings.
　 Ultraviolet ray exposure during the treatment activate the decomposition of sodium hypochlorite and promoted the fading of the dyes. Fiber also got degradation by the treatment.

DESCENTE SPORTS SCIENCE Vol.19/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE