Predictions from two previously published models and a new model for the relative change in cuticular permeability with boiling point, octanol/air partition coefficient, and/or molar volume of a wide range of diffusants (not including ions and large hydrophilic compounds) are compared with each other and to experimental data sets not used for model parameterization. While the models work in a similar way for all cuticles for which data are available, it is not yet possible to predict in absolute terms the permeability of any cuticles for which no data are available—that is, while the slope of a plot representing the change in permeability with diffusant properties is predictable, the position of the linear relationship along the ordinate needs to be determined experimentally for each type of cuticle at or near the relevant temperature(s).