Studies which have been done with human ~'s regarding the possibility of dermo-optical perception or sensitivity are conflicting. Further work is indicated as necessary before any clear-cut conclusions can be drawn. The present research attempted to investigate (1) the possibility of dermo-optical sensitivity in the rat; (2) the particular conditions Winder which this sensitivity might be demonstrated, and/or, if (3) it was found to exist at all in the rat. The results indicated significant differences in performance between experimental and control Ss. It was concluded that rats had dermo-optical sensitivity, and that this quality or ability was most prevalent when the Ss were shaven previous to their exposure to the relevant stimuli.