Background: The leaves of Sesbania grandiflora have been used in local traditional medicine since ancient times. In the present study we investigated, in vivo and in vitro, the potential health benefits of various fractions of the ethanolic extract of these leaves. Materials and methods: Crude ethanolic extract (CEE) of S. grandiflora leaves was partitioned into ethyl acetate soluble fraction (EASF), petroleum ether soluble fraction (PSF), carbon tetrachloride soluble fraction (CTSF), chloroform soluble fraction (CSF), and water soluble fraction (WSF). The extracts were evaluated for their thrombolytic, membrane stabilizing (anti-inflammatory), antimicrobial, and antidiarrheal activities. The results were compared to the effects of standard drugs: streptokinase for the thrombolytic, acetylsalicylic acid (ASA) for the membrane stabilizing, kanamycin for antimicrobial, and loperamide for the antidiarrheal activities. Results: For thrombolysis, EASF showed the highest % of clot lysis (59.6%) among all fractions, while streptokinase and water resulted in 69.2% and 3.1% clot lysis respectively. With respect to the membrane stabilizing activity, the EASF significantly inhibited the hemolysis of human erythrocytes induced by hypotonic solution (64.3±0.6%) or by heat (57.2±0.7%). The other fractions exhibited no membrane stabilizing effect. By contrast ASA resulted in 73.9±0.3% inhibition of osmotically induced hemolysis and a slightly lower level of inhibition in the case of heat-induced hemolysis (70.1±0.3%). The antidiarrheal activity was evaluated in the mouse model. The unfractionated, CEE reduced the number of defecation episodes by 25.0% at a dose of 200 mg/kg and by 41.1% at dose 400 mg/kg body weight. All extract fractions exhibited significant antibacterial activity, which was higher against Gram negative bacteria than Gram positive bacteria. Since the pharmacological activities of S. grandiflora are due to the presence of bioactive compounds we detected and quantified the presence of significant levels of flavonoid and tannin substances. Conclusion: Leaves of Sesbania grandiflora have the potential to be used as a remedy for thrombosis, diarrhea, and inflammatory diseases and against few important bacterial pathogens. [ABSTRACT FROM AUTHOR]