The Royal College of Surgeons (RCS) rat is an animal with genetically transmitted progressive retinal dystrophy. We compared histopathologically the RCS rat retina with normal age-matched control retinas (Long-Evans rats) using light and scanning electron microscopy. Retinal degeneration begins with alteration of the rod outer segments. There is a progressive involvement of the entire retina, with all layers affected by 45 days. The three-dimensional view obtained with scanning electron microscopy provides another perspective on the pathogenetic changes of the RCS retina.