Between the anterior ciliary muscle tips in normal and glaucomatous eyes, different forms of plaque material were found within the intermuscular connective tissue. These plaques derive from either the sheaths of the elastic-like fibers or the elastic tendons of the anterior ciliary muscle tips. In addition, there are plaques which have the characteristics of the hyalinized basement membranes of the trabecular beams. The quantitative evaluation of all three types of ciliary muscle (c.m.) plaques showed that in normal eyes the amount of c.m. plaques increases with age and correlates with the amount of plaques in the inner wall of Schlemm's canal. In cases of chronic simple glaucoma the amount of c.m. plaques did not significantly correlate with age, but the absolute amount of this material was significantly higher than in normal eyes. No correlation between inner wall and c.m. plaques was found, indicating that in glaucoma additional factors besides age contribute to plaque formation.