Abstract One of the best-known multi-purpose medicinal plants in Southern Africa, Sutherlandia frutescens subsp. microphylla (family: Fabaceae/Leguminosa), is used for a wide range of conditions, including cancer, viral diseases and inflammatory conditions. Little scientific data has been documented on the mechanism by which Sutherlandia frutescens acts on the immune system. Phagocyte derived reactive oxygen species, such as hydrogen peroxide and superoxide radicals, are responsible for the pathogenesis of various inflammatory conditions. Anti-inflammatory properties of various medicinal-plant extracts have been explained, at least in part, by their antioxidant activities. We investigated the effects of a hot water extract of Sutherlandia frutescens on both luminol and lucigenin enhanced chemiluminescence of neutrophils stimulated with l-formyl- l-methionyl- l-leucyl- l-phenylalanine (FMLP) as well as its superoxide and hydrogen peroxide scavenging properties in a cell free system. The results indicate that Sutherlandia frutescens extract possesses superoxide as well as hydrogen peroxide scavenging activities at concentrations as low as 10 μg/ml, which could account for some of the anti-inflammatory properties that have been described.