This paper presents quantitative structure-activity relationship (QSAR) models for a series of 30 anionic azo dyes applied to cellulose fiber by comparative molecular field analysis. Two forms of the dye molecules (neutral and anionic) are compared. Neutral structures give better statistical results than the anionic species. The electronic and structural properties of these dyes were calculated by the semiempirical AM1 method. The results indicate the predominance of electrostatic interactions in dye-cellulose binding. The dominant contribution of the HOMO orbital molecular energy, used as descriptor, can be explained by the donor ability of the dye molecules in the dye adsorption on cellulose.