The feasibility of the derivatives of polyethylene glycol as leveling agents in the dyeing process of wool was studied. The interaction between the polymers and dyes affected not only the dyeing rate of supermilling acid dyes on wool but also the absorption spectrum of the dyes. The presence of the polymers improved leveling properties. The dyeing rate was slower in the presence of the polymer than without the polymer. The lower the concentration of dyes, the greater the effect of the polymers in the dyeing process was. The color fastnesses to rubbing, washing, and perspiration of the dyed wool fabrics with the polymer were good. (c) 2005 Wiley Periodicals, Inc.