The bacterial and fungal inhibitory efficiency of the Argemone mexicana Linn. (Papaveraceae) and Aerva javanica (Burm.f.) Juss. Ex. Schult. (Amaranthaceae) were evaluated against bacterial species like Staphylococus aureus, Streptococcus pyrogens, Klebsiella pneumonia and Escherichia coli and two fungal species such as Aspergillus niger and Penicillium notatum. The susceptibility of the microorganism to the extracts of these plants was compared with each other and with selected antibiotics. All these plants were effective against three of the pathogenic microorganisms. This in vitro study corroborated the antimicrobial activity of the selected plants used in folklore medicine. Key words: Antibacterial activity, Antifungal activity, Disc diffusion method, Well diffusion method.