A review by Wortmann et al of the mechanism of dye diffusion into wool interpreted experimental data that generally agreed with data obtained by Leeder et al at the CSIRO Division of Wool Technology. This research used a transmission electron microscope to follow the diffusion of specially synthesized dyes containing nuclear dense atoms into wool. Despite the general agreement between Wortmann and Leeder, this letter to the editor comments on two points in the review. The comments relate to a two stage cell membrane complex (CMC) diffusion model for wool dyeing and to the relative importance of the CMC in the mechanism of the diffusion into wool. The major area of disagreement is in the function of the accessible, readily swollen intercellular cement component of the CMC in dye diffusion into wool. Whereas Wortmann considers this component unimportant, Leeder believes a large body of evidence supports the importance of the intercellular cement component in wool dyeing because it is the preferred path by which dye molecules reach cortical cells. 6 refs.