The corneal cells are destroyed within a 10 mm diameter circular belt by liquid nitrogen application in vivo. The endothelial regeneration is followed from day to day using endothelial flat preparation technic, and is compared to the corneal thickness measurement and to the estimation of transparency. From the 5th day, Descemet's membrane is entirely covered by the regenerated endothelium; from this time, both thickness and transparency of the stroma become normal. Therefore, in spite of the persitence of morphologic abnormalities, the regenerating endothelial cells preserve or obtain again very rapidly their specific function of a barrier against hydration of the stroma.