An immunohistochemical study was performed to observe cellular proliferation on the surface of implanted intraocular lenses (IOLs) in rabbit eyes. Rabbits were killed 3-28 days postoperatively. The removed IOLs were examined by an immunoperoxidase staining method using anti-fibronectin antibodies. The immunoreactivity for fibronectin was detected in macrophages and multinucleated giant cells attached to the IOL surface. Prominent stains were observed in these cells 1 week after the operation, and staining for fibronectin was less intense in the specimens 2 and 4 weeks after implantation. Fibronectin is produced by macrophages and multinucleated giant cells on the IOL surface, and might play important role in cellular adhesion and motility. Fibronectin immunoreactivity decreased with time and it may be related to cellular activity.