Purpose: In this study, three important medicinal plants (Enhydra fluctuans Lour, Clerodendrum viscosum Vent and Andrographis peniculata Wall) of Bangladesh were investigated to analyze their antimicrobial and cytotoxic activities against some pathogenic microorganisms and Artemia salina (brine shrimp nauplii). Methods: The coarse powder material of leaves of each plant was extracted separately with methanol and acetone to yield methanol extracts of leaves of Enhydra fluctuans (MLE), Clerodendrum viscosum (MLC) and Andrographis peniculata (MLA), and acetone extracts of leaves of Enhydra fluctuans (ALE), Clerodendrum viscosum (ALC) and Andrographis peniculata (ALA). The disc diffusion method and the method described by Meyer were used to determine the antimicrobial and cytotoxic activities of each plant extract. Results: Among the test samples, MLE and ALE showed comparatively better antimicrobial activity against a number of bacteria and fungi with inhibition zones in the range of 06-15 mm and according to the intensity of activity, the efficacy against microorganisms were found in the order of Enhydra fluctuans> Andrographi speniculata> Clerodendrum viscosum. In cytotoxicity assay, all samples were found to be active against brine shrimp nauplii (Artemia salina) and ALA produced lowest LC50 value (7.03 μg/ml). Conclusion: Enhydra fluctuans and Andrographi speniculata possesses significant antimicrobial and cytotoxic activities
