Beta glucans, β-1,3-glucans (glucans) are chains of sugars (polysaccharides) naturally occurring in the cell walls of plants such as cereals, bacteria and fungi. They are gaining attention not only as an important food supplement but also as an immunostimulant and potential drug. It has been known since prehistoric times that mushrooms have medicinal properties. Glucans effect various branches of the immune system and there are numerous animal and human studies showing remarkable activity against a wide variety of tumours. This paper represents an up-to-date review of glucans and their role in various immune reactions and the treatment of cancer. It also cites studies showing their potential use for wound healing and skin health, chronic respiratory problems in children, alleviation of allergic problems and reducing cholesterol levels. Additional lesser-known effects of glucan include improvements in colitis, obesity, or Lyme disease The authors conclude that glucans are an important immunomodulator. They believe that glucans will soon move from food supplement to widely accepted drug.