A photographic reference scale representing six levels of conjunctival hyperemia has been developed for the assessment of responses to contact lenses. The scale has been found to be capable of detecting statistically significant differences in conjunctival hyperemia responses between samples of hard, soft, and noncontact lens wearers. For experienced observers, inter- and intraobserver reliability was found to be high and the conclusion is drawn that this type of scale is potentially useful in research and clinical applications.