The electron microscopical findings in the outer nuclear layer of the rabbit retina following exposure of ruby laser beams are described: half-an-hour following laser coagulation the nuclei show a conglomeration of the chromatin. 20 h after coagulation, fragments of outer and inner segments of the rods are observed in the outer nuclear layer. Some cells also contain homogeneous and dense nuclear aggregations of small electrondense granules. 25 h after laser application, the alterations in the nuclei are more pronounced : the chromatin shows a marginal condensation or has sickle-shaped appearance. 35 h after coagulation, Müller cells appear in the outer nuclear layer. 10 h later these cells accumulate, whereas the outer nuclear cells decrease. Between 45 and 116 h, macrophages and Müller cells are observed in the outer nuclear layer.