Stephanostema is a monotypic genus whose sole specie Stephanostema stenocarpum is endemic to Tanzania. The liquid from boiled roots of this plant is being used by the local communities as a remedy of stomach-ache related ailments. The aim of the study was to evaluate antimicrobial activity of S. stenocarpum extracts against some common bacterial and fungal pathogens in domesticated animals and examine whether the crude extracts found active have cytotoxic effect or not. The standard growth inhibition technique was used for in vitro antimicrobial activity assay and the brine shrimp (BST) test was used to evaluate cytotoxicity of the extracts. Ethanolic extracts exhibited bacterial inhibitory growth activity against animal bacteria pathogens: Streptococcus agalactiae, Staphylococcus aureus, Salmonella gallinarum and Escherichia coli, but not active against the fungal strains tested. The study also showed that the extracts have no cytotoxicity effects. These results provide baseline information on the medicinal potential of S. stenocarpum as a new potential source of veterinary medicines.