Iris illumination typically causes specular highlighting both within the pupil and iris. This lighting variation is intended to be masked in the preprocessing stage. By removing or reducing these specular highlights, it is thought that a more accurate template could be made, improving the matching results. In an attempt to reduce these specular highlights we propose a diffuse illumination system. To determine if iris recognition performance is enhanced by this diffuse illumination system, we examine whether specular highlights were reduced within the pupil and iris, as well as analyze matching results obtained by several iris algorithms.