Epidermal growth factor (EGF) was injected into the anterior chambers of 12 rhesus monkeys after the denudation of the central corneal endothelium during autograft transplantation. The animals were treated both at the time of surgery and three weeks after surgery. Clinical appearance and corneal thickness were monitored until the corneas were removed by penetrating keratoplasty ten weeks after the initial treatment. Flat preparations of the corneas showed significantly more endothelial cells in the central corneas of the EGF-treated eyes compared with the control eyes. These findings indicate that EGF is effective in replenishing the corneal endothelium after injury.