Abstract: It has been well known since ancient times that plants and spices have antimicrobial activity. There has been a considerable interest to use plants and spices for the elimination of microorganisms because of increasing antibiotic resistance of microorganisms. Petroleum ether, chloroform, ethyl acetate, acetone, methanol and aqueous root extracts of Cocculus hirsutus were evaluated for antimicrobial activity against clinically important bacteria viz., Escherichia coli (MTCC 1195), Enterobacter aerogens (MTCC 2823), Klebsiella pneumoniae (MTCC 2405), Salmonella typhi (MTCC 733), Proteus vulgaris (MTCC 1771) and Pseudomonas aeruginosa (MTCC 2642) (gram-negative), Staphylococcus aureus (MTCC 1430) and Bacillus cereus (MTCC 1272) (gram-positive). The in vitro antimicrobial activity was performed by agar disc diffusion method. The results showed the chloroform root extract of Cocculus hirsutus highly affected the activity of Pseudomonas aeruginosa and Bacillus cereus. The inhibition against Staphylococcus aureus and Enterobacter aerogens was moderate and the remaining bacterial strains had no activity. This study suggests that the root of Cocculus hirsutus obtained by infusion can be used in the treatment various bacterial diseases.