Abstract: The strong regenerative capacities of planarian have been considered to reside in a population of stem cells called the 'neoblasts'. These cells are the only mitotic cells in planarians, they play a great role in giving rise to the lost cells and reforming the missing structures. By the means of migrating, proliferating and differentiating of the neoblasts, any tiny amputated fragment of their body can regenerate into a complete individual. Advances in the study of stem cells in planarians are summered in this paper.