Gum arabic (GA) is a branched-chain, complex polysaccharide, either neutral or slightly acidic, found as a mixed calcium, magnesium and potassium salt of a polysaccharidic acid. The backbone is composed of 1,3-linked beta-D-galactopyranosyl units. The side chains are composed of two to five 1,3-linked beta-D-galactopyranosyl units, joined to the main chain by 1,6-linkages. Pharmacologically, GA has been claimed to act as an anti-oxidant, and to protect against experimental hepatic-, renal- and cardiac toxicities in rats. These reports could not be confirmed by others. GA has been claimed to alleviate the adverse effects of chronic renal failure in humans. This could not be corroborated experimentally in rats. Reports on the effects of GA on lipid metabolism in humans and rats are at variance, but mostly suggest that GA ingestion can reduce plasma cholesterol concentrations in rats. GA has proabsorptive properties and can be used in diarrhoea. It enhances dental remineralization, and has some antimicrobial activity, suggesting a possible use in dentistry. GA has been shown to have an adverse effect on electrolyte balance and vitamin D in mice, and to cause hypersensitivity in humans. More studies are needed before the pharmacological properties of GA can be utilized in therapy.