alpha-Glucans are present in virtually all domains of life, and these glucose chains linked by alpha-1,4- and alpha-1,6-linked branches form the most important storage carbohydrates in cells. It is likely for this reason that alpha-glucans are not generally considered as bioactive molecules as beta-glucans are. Nevertheless, it is known that depending on their source, many alpha-glucans play important roles as modulators of immune response. Recent efforts have attempted to elucidate the mechanisms through which alpha-glucans exert their immunostimulant effects; however, the main challenge is the accurate identification of the receptors of immune cells involved in their recognition. Here, we review the adjuvant properties reported for some polysaccharides and ultimately focus on alpha-glucans and how their structural characteristics, such as molecular weight, solubility and derivatization, influence their immunostimulatory properties. As a final point, we discuss the potential and associated challenges of using these polysaccharides as adjuvants, particularly in mucosal vaccination. (C) 2017 Elsevier Ltd. All rights reserved.