Long-term steroid therapy is associated with production of a posterior subcapsular cataract (PSC). Five steroid-associated cataractous lenses were studied, using light, scanning, and transmission electron microscopy. Anterior, equatorial, and posterior regions were examined. Findings were compared with five age-matched senile PSCs and five nuclear cataractous lenses with no cortical opacities. The posterior polar region of steroid-associated cataractous lenses consists of (1) a superficial zone of liquefaction and (2) a deep zone of segmentally swollen lens fibers. Nucleated lens fibers are present in posterior cortical regions. Cytoplasm at knob and socket junctions had become lucent and plasma membranes were disappearing, leaving empty spaces. Laminated membranous configurations were seen. Although the same basic histopathologic abnormalities were found in steroid-associated cataracts and in nonsteroid senile PSCs, it is their organization and localization that may be the distinguishing characteristics of the steroid-associated cataract.