It has long been thought that functional regeneration of the injured central nervous system (CNS) is impossible, as Santiago Ramóny Cajal described in the early 20th century, “once the devel-opment was ended, the fonts of growth and regeneration ... dried up irrevocably”. In mammalian neural development, most neuronal production (neurogenesis) occurs in the embryonic stage. How-ever, recent findings indicate that neurogenesis continues in the olfactory bulb, hippocampus, and dentate gyrus of adult mammalian animals, from the neural stem cells (NSCs). Recently developed techniques have made it possible to isolate, culture, and grow pluripotent self-renewing NSCs from both embryonic and adult brains. This basic research is attracting a lot of attention because of the hope that it will lead to regeneration and reconstruction therapy for the damaged CNS. In this review, recent findings on the stem cell biology of the CNS and strategies for its potential therapeutic application will be discussed.