The repair of wounds of the cornea made by removing the full thickness of epithelium was studied in mice, both in vivo and in organ cultures. Repair of wounds 1 to 1.4 mm diameter was complete in 12 to 16 hr. Elongated epithelial cells were arranged radially about the margins of these small circular wounds. In large, irregularly shaped wounds, the cells frequently lay with their long axes at a tangent to the wound margin. On cells with this arrangement, leading lamellae and numberous short filopodia were present, but they were not on the radially arranged cells. The tangential orientation of the epithelial cells, usually seen at convex parts of the margins, was believed to be associated with arrest of the advance of these areas. Participation of the cells of the peripheral cornea in the movement of the epithelium was evident by the movement of India ink markers placed in them and also by the piling up of cells at incisions made across the direction of movement of the epithelium. The concept of cells rolling over each other at the edge of the wound was not supported. They appeared to move as a mass without significant changes in their relative positions.