Reflectance measurements on dyed nylon fabric showed that the color yield (depth of color per unit amount of dye in the fiber) of dyeings produced by the DuPont "Infinity" process was higher than that of conventional dyeings produced by controlled uptake of the dye using a gradual temperature increase of the dye solution. Microscopic examination of cross sections of dyed multifilament yam confirmed that this dyeing process gave unsymmetrical coloration of the nylon filaments on the exposed yam surfaces, with the filaments in the interior of the yam bundle remaining undyed. This particular dye distribution arises from dyeing under conditions where the rate of dye adsorption is high but the rate of its diffusion into the filaments is relatively low, Although the dye is mainly located on the multifilament yam surfaces, analysis of the percentage loss of color strength of the dyed fabrics on repeated washing, or on exposure to light or to ozone under wet conditions, indicated little difference in color fastness to these agencies in comparison with conventional dyeings where all of the filaments were uniformly dyed. The problem of colorant formulation for the "Infinity" dyeing process is discussed.