Abstract: In the present study a comparison on antimicrobial potency of three common weeds i.e. Cannabis sativa, Parthenium hysterophorus and Calotropis procera, were tested by agar well diffusion method against the six common pathogens namely, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Saccharomyces cerevisiae. The in vitro study revealed that organic leaves extract of weeds were more effective than aqueous extract. Among the three tested weeds, methanolic extract of C. sativa was found to be most effective as compare to other weeds. It showed maximum zone of inhibition of 26.3 and 25.6 mm against Bacillus subtilis and Staphylococcus aureus with lowest MIC of 1.56 mg mL‾1. This study revealed that the organic leaves extract of C. sativa showed good antibacterial activity and can be explored for developing antibacterial drugs.