This review summarizes recent breakthroughs in studies regarding proliferation of adult stem cells which complement and extend our knowledge to various aspects of cell biology and signal pathways. In recent years, many interesting results and discoveries were achieved regarding the proliferative properties of stem cells. In vitro expansion of stem cells may benefit from high proliferation rates, which can produce a large amount of cells to regenerate tissue defects. Meanwhile, optimizing the culture conditions for stem cell propagation is helpful in maintaining the pluripotency and differentiation potential of stem cells, which are critical for tissue engineering and regenerative medicine. Additionally, understanding the proliferation of stem cells may help us to uncover new mechanisms of drug resistance, since stem cells are believed to play an important role in drug resistance. In this review, we focus on signaling pathways regulating the proliferation of various stem cells isolated from adult tissues. We also emphasize the significance of stem cells proliferation in cell research, as well as rapid propagation of adult stem cells for regenerative medicine.