Abstract: The present study reports the antibacterial potency of the methanolic extract of 25 common weeds, Abutilon indicum, Acalypha indica, Ageratum conyzoides, Alangium platanifolium, Anisomeles sp., Boerhavia diffusa, Cardiospermum helicacabum Cassia alata, Centella asiatica, Coccinia grandis, Commelina benghalensis, Corchorus sp., Croton sparsiflorus, Dodonea viscosa, Hyptis sauveolens, Lantana camara, Leonotis nepetifolia, Mimosa pudica, Martinea annua, Occimum americanum, Oldenlandia umbellata, Parthenium hysterophorus, Solanum nigrum, Tinospora cordifolia and Xanthium stromarium belonging to 15 different families. The plants were collected from the districts of Chengalpet, Chennai, Kancheepuram, Vellore and Tiruvellore belonging to the Northern part of the State of Tamil Nadu. The antibacterial property were determined using disc diffusion method on the following species of bacteria, i.e., Bacillus subtilis (MTCC121), Escherichia coli (MTCC443), Staphylococcus aureus (MTCC96), Streptococcus mutans (MTCC890) and Klebsiella pneumoniae (MTCC1320). The following weeds, Parthenium hysterophorus, Leonotis nepetifolia, Martinea annua and Xanthium stromarium have showed positive zone of inhibition to all the bacteria studied.