The in vitro antimicrobial activity of different varieties of Piper betle Linn. leaf stalk extracts were studied against human pathogenic bacteria and phytopathogenic fungi by comparing the results with standard microbial susceptibility testing biodiscs. The ethyl acetate and ethanol extracts of all the four varieties have shown significant activity against bacteria Vibrio cholerae ogawa, Staphylococcus aureus, Diplococcus pneumoniae and Klebsiella aerogenes. The hexane and benzene extracts have shown moderate activity, while other extracts have shown poor or no activity. In the same way ethyl acetate and ethanol extracts of all the varieties have shown moderate to significant activity against most of the fungi tested, while other extracts showed poor or moderate activity.

        Key words: antimicrobial activity, Piper betle Linn.