Abstract: “Plants contain natural products which have been recognized as building blocks for primary health care. Sterculiar tragacantha Lindl, used traditionally in Nigeria for the treatment of boils, diarrhea, gonorrhea, edema, gout, whitlow, fevers and malaria is one of such plants. The prevalence of drug resistant pathogenic microbes as well as the oxidative damage to cells by excess free radicals that lead to degenerate diseases, constitute major health hazards to man. In this regard, extracts of the stem bark of S. tragacantha Lindl was investigated for their toxicity to brine shrimps and ability to scavenge hydroxyl radical and inhibit microbial growth. Air dried and ground stem bark of the plant was extracted with methanol and partitioned in n-hexane and ethyl acetate. Hydroxyl radical scavenging assay of the three extracts obtained revealed that the percentage inhibition for all the extracts was above 90% at 0.625 mg/ml which is higher than that of one of the antioxidant standard (ascorb”

Keywords: Phytochemicals, hydroxyl radical, toxicity, antimicrobial, Sterculiar tragacantha