A case is presented of a girl, aged 18, born of parents who were first cousins. She had an atypical retinitis pigmentosa with involvement of the macula. The neurologic examination showed diffuse disease of the central nervous system, as seen in Friedreich’s ataxia. An additional finding (hitherto undescribed) was that of a malformation of the red blood cells. These cells had a peculiar crenated appearance, due to the presence of pseudopods or protoplasmic projections varying in size and shape. They were constantly present in stained blood films taken one year apart. A similar finding in a younger brother, with beginning retinal pigmentary degeneration, added additional proof of the hereditary nature of the condition.