Reduced glutathione is an antioxidant; it is thought to be essential for normal functioning of the central nervous system. We have examined by means of intmunocytochemistry, the distribution of reduced glutathione in the retina of the rabbit. Strong immunoreactivity was present in the radial glial cells (Müller cells) and in the horizontal cells. Other neuronal elements contained only low, or no detectable levels of immunoreactivity for reduced glutathione. The presence of an abundance of reduced glutathione in glial cells suggests that glia play a critical role in regulating the content of potentially damaging oxidative species in the central nervous system.