Six eyes with persistent corneal epithelial defects of various etiologies were treated in a randomized, prospective, double-masked study to evaluate the effect of fibronectin on corneal epithelial wound healing. Study eyes received homologous human fibronectin (300 micrograms/ml), mixed with gentamicin and artificial tears, 4 times a day. Control eyes received the mixture of gentamicin and artificial tears. If no healing occurred after 2 weeks, the drug was unmasked and where control drops had been given, the mixture containing fibronectin was administered in open-label fashion. All 4 eyes in diabetic patients had successful epithelial healing when treated with the fibronectin solution. The 2 remaining corneas, which had defects secondary to a thermal injury and a presumed infectious etiology, did not heal with fibronectin.