Young MJ. Stem cells in the mammalian eye: a tool for retinal repair. APMIS 2005;113:845–57. Degenerative diseases and traumatic injuries of the central nervous system (CNS) are major causes of long-term disability, whether such insults impact the brain, retina, or spinal cord. Substantial tissue destruction can be sustained by these complex structures without loss of life, while the lack of effective CNS regeneration frequently results in a marked degradation in quality of life. Only recently has it become clear that an enormous potential for regeneration is present within the mammalian CNS. The challenge now presented to researchers is to harness this potential to treat disease. Recent studies showing that stem and progenitor cells can be isolated from the mammalian retina have prompted many researchers to develop strategies aimed at restoring function to the diseased retina. This review summarizes a number of issues related to this goal, including retinal development, transplantation immunology, tissue engineering, and large animal studies. The application of these divergent disciplines to stem cell technology is vital to the development of the novel strategies needed to make retinal transplantation a clinical success.