The adsorption of acid dyes on undrawn and drawn nylon 6 fibers have been investigated. The dyes used are C.I. Acid Orange 7 and C.I. Acid B1ue 113. The saturation of Orange 7 which had small molecular weight and short molecular chain was nearly equal to amino end group content of the undrawn fiber. But the saturation of Blue 113 which had larger molecular weight and two sulphonic acid groups was about 0.7 of amino end group content of the undrawn fiber. The saturation of dye is reduced a little as the draw ratio increases from 1.0 to 3,4.