The phytochemicals screening investigation for aqueous extract of Datura stramonium leaves revealed the presence of carbohydrates, tannins, steroidal glycosides, phenols and saponins. The antimicrobial potential of the extracts of leaves were evaluated against clinical bacterial isolates like Bacillus, Escherichia coli, Staphylococcus aureus, Pseudomonas, Sarcina and Klebsiella. The results showed the exhibition of antibacterial activity against all isolates and revealed higher sensitivity for Sarcina and Staphylococcus aureus. The present study also reveals that, the assay carried out on alpha-amylase enzyme showed the dose-dependent increase in inhibitory effect with IC50 730 μg. The in vitro studies clearly indicate that the extract of D. stramonium leaves has antimicrobial activity and α-amylase enzyme inhibitory activity and hence may be considered as a potential candidate for the management of diabetes mellitus.