We performed posterior chamber lens implantation (IOL) in three monkey eyes. All pseudophakic eyes developed a ring-shaped opacity, appearing on the IOL optics along the anterior capsule incision line. Transmission electron microscopic study revealed that the anterior capsule opacification was composed of proliferated cellular and extracellular components between the anterior capsule and the IOL optics. The proliferated cells looked like fibroblasts, but they were connected by desmosomes and covered by basal lamina. These histologic findings represented morphological features of epithelial cells, probably lens epithelial cells. Extracellular components consisted of collagen fibers, microfibrils, and basal lamina-like materials.