Abstract: This article presents an overview of the recent advances into the health promoting potentials of oat β-glucan. Oat β-glucan (OβG) consists mainly of the linear polysaccharide (1→3), (1→4)-β-D-glucan and is often called β-glucan. This soluble oat fiber is able to attenuate blood postprandial glycemic and insulinemic responses, to lower blood total cholesterol and low-density lipoprotein (LDL) cholesterol, and to improve high-density lipoprotein (HDL) cholesterol and blood lipid profiles as well as to maintain body weight. Thus, OβG intake is beneficial in the prevention, treatment, and control of diabetes and cardiovascular diseases. In addition, OβG can stimulate immune functions by activating monocytes/macrophages and increasing the amounts of immunoglobulin, NK cells, killer T-cells, and so on, which will improve resistance to cancer and infectious and parasitic diseases, as well as increase biological therapies and their prevention. All these health benefits of OβG may be explained by its physicochemical properties (such as viscosity, molecular weight) which can be affected by extraction methods and its behavior in gastrointestinal tract. Articles documenting these health benefits and effects are reviewed.