Wool fibers treated with oxygen low-temperature plasma, liquid ammonia (NH3), and high-pressure (HP) steam were dyed with two acid and three disperse dyes. Rate of dyeing, saturation dye uptake, and dyeing transition temperature were measured. Rate of dyeing of the O-2 plasma, NH3, and HP steam-treated wools increased with acid dyes, whereas it did not increase with disperse dyes. Although dyeing transition temperature for acid dyes was decreased by the plasma, NH3, and HP steam treatments, the temperature for disperse dyes was not changed by the treatments. Therefore, it seems that acid dyes penetrate by the intercellular diffusion through the interscale Cell Membrane Complex (CMC) of wool, whereas disperse dyes penetrate by the intracellular diffusion through the intrascale cuticle surface independently with CMC relaxation by the treatments.