[ ($1{ o}3$) ], ($1{ o}4$)-${eta}$-D-glucans(${eta}-glucans$) are a major component of the cell walls of grasses as a component of the cereal endosperm and aleurone cell walls. Although ${eta}-glucans$ exist in all cereals, their concentration is highest in oats and barley. Genetic and environmental differences are found in total ${eta}-glucan$ content. Both oats and barley ${eta}-glucans$ have cholesterol-lowering effects. This suggests possible use as food additives. Structural characterization of ${eta}-glucan$ is important because structure can influence physical and physiological properties. In this review, ${eta}-glucans$ of barley and oats are discussed in details including structure, chemical and physical properties, and nutritional implications. The use of barley and oat products as well as ${eta}-glucan$ as a food additive continues to increase. This can provide an additional market for barley and oats, thus increasing the value of the crops.