摘要Background: Diarrhea can be caused by pathogenic microorganisms and chemicals. In view of this, Byrsocarpus coccineus Schum and Thonn (Connaraceae) was used to treat diarrhea induced by castor oil or bacteria in Wistar albino rats. Methods: Qualitative and quantitative analyses of an aqueous root back extract of B. coccineus were made and the acute toxicity, antidiarrhea properties, and in vitro and in vivo antimicrobial activities of the extract were investigated in rats. Results: The phytochemical analysis of the root bark extract revealed the presence of flavonoids, alkaloid, saponins, tannins, and phenols. The quantitative analysis showed that saponins formed 10.6％ of the extract, tannins 7.6％, flavonoids 6.2％, phenol 5.8％ and alkaloids 4.4％. A dose limit of 5000 mg/kg was safe to use in the rats. At a dose of 100 mg/kg, the extract decreased distance travelled by activated charcoal in the gastrointestinal tract, frequency of defecation, and number of unformed faeces caused by castor oil-induced diarrhea, and led to 74.96％ inhibition of the diarrhea effects. Escherichia coli and Salmonella pullorum were susceptible to higher concen-trations of the extract with a minimum inhibitory concentration of 0.3125 mg/mL. E. coli-infected rats showed depression, weight loss, anorexia, diarrhea, and weak-ness, which was ameliorated by the extract on day 2 post treatment. Observed con-gestion, cellular infiltration and necrosis of the liver, intestine and kidney following infection were improved by the extract. Conclusion: B. coccineus extract can be used in the treatment of anaemia, and castor oil- and E. coli-induced diarrhea in rats.