Marine organisms are potential sources of unique natural products with pharmacological and biological activities. In mariculture, diseases of microbial origin can cause huge economic losses worldwide. The evolution of microorganism resistance to antibiotics has resulted in a growing need for new antibacterial compounds that are effective in veterinary medicine and characterized by limited undesirable side effects. Increased attention has recently been turned to plants as a promising source for metabolites with antimicrobial activity. Achyranthes aspera is one such important plant with various established pharmacological properties. The aim of the present study was to assess the antibacterial activity of the Achyranthes aspera extract against Vibrio alginolyticus 1374. Aqueous extract of Achyranthes aspera was prepared. Different concentrations of the root and stem extracts of Achyranthes aspera were transferred to the agar plates, which had been streaked with the bacterium Vibrio alginolyticus; 1374. The plates were incubated aerobically at 37°C for 24 h and the zones of inhibition were measured using well diffusion method. Achyranthes aspera extract showed significant zones of inhibition. Achyranthes aspera showed marked antibacterial activity against Vibrio alginolyticus 1374.