The posterior sclera of three normal eyes and five staphylomatous, myopic eyes was examined by electron microscopy. The following notable differences were found in myopic sclera: a predominantly lamellar, collagen fiber bundle arrangement; a reduction in the diameter of the fibrils; a greater dispersion for the range of fibril diameters; an increase in unusual star-shaped fibrils on cross section; and a greater prevalence of fibril groups with uniform but extremely fine diameters. These findings essentially agree with those in other studies of the myopic sclera. The ultramicroscopic changes encountered inpathologic myopia are judged to be compatible with an abnormal proteoglycan composition of the interfibrillary substance in the ectatic sclera.