Abstract: The ethanolic extract of the leaf of Mirabilis jalapa was tested for antimicrobial activity against five pathogenic bacterial strains: Escherichia coli, Staphylococcus aureus, Salmonella typhi, Bacillus cereus and Klebsiella pneumoniae. Antagonistic activities of toxins from nine strains of bacteria and four fungi isolated from refuse dumps was also tested on the pathogens. The isolates producing the toxins were identified as Pseudomonas sp., Acinetobacter sp., Corynebacterium sp., Actinomyces sp., Clostridium sp., Bacillus sp., Shigella sp., Proteus sp. Enterobacter sp., Penicillium sp., Aspergillus flavus, Aspergillus niger and Aspergillus repens. The agar ditch diffusion method was used was used for the in vitro antimicrobial bioassay. The leaf extract was found to have a higher antimicrobial efficacy than the toxins from the organisms as shown in the growth inhibition indices. The highest zone of inhibition of leaf extract was 13.0 mm and the least 4.0 mm. The highest zone of inhibition of bacteria isolates was 9.0 mm and the least 3.5 mm while the highest zone of inhibition of fungi isolates was 13.0 mm and the least 2.0 mm. Fungi isolates produce toxins with broad spectrum of activity. However the commercial antibiotics was found to be more potent than the toxins or the extract; But with narrower spectrum of activity. Phytochemical screening of the extract revealed the presence of tannins, saponins, alkaloids and cardiac glycosides. The toxins and the plant extract possess’ antimicrobial activities comparable to conventional antibiotics; and can thus be a good source of agents for biocontrol and chemotherapy.