Black ginseng is a processed ginseng which prepared by steaming and drying of white or red ginseng for several times (usually 9). This process resulting in extensive changes in types and amounts of several secondary metabolites. Thus, primary ginsenosides (the main active inredients in ginseng) were transformed into less polar derivatives by steaming. In addition, apparent changes happened to other secondary metabolites such as the increasing of phenolic compounds, reducing sugars and acidic polysaccharides as well as the decrease in concentrations of free amino acids and total polysaccharides. Furthermore, the presence of some Maillard reaction products like maltol was also engaged. These obvious chemical changes were associated with a noticeable superiority for black ginseng over white and red ginseng in most of the comparative biological studies including anticarcinogenic, immunomodulatory, anti-Inflammatory, antidiabetic, hepatoprotective, antioxidant and tonic effects.