The aims of this study were to determine the total population of coliform bacteria in the samples collected from diarrhea associated patients from the local area of Bangladesh and to examine the antibacterial efficacy of leaf extracts of Moringa oleifera (Moringaceae) against the isolated coliform bacteria. The coliform bacteria detected in these samples by some microbial-biochemical tests such as Escherichia coli, Shigella dysenteriae, Salmonella sp., Enterobacter sp., Klebsiella pneumoniae and Serratia marcescens. The total isolation rate of coliform bacterial species was ranged from 38.01-3.51%. At the concentration of 300 ig/disc, the organic extracts of hexane, chloroform, ethyl acetate and methanol extracts of Moringa oleifera leaf exhibited a remarkable antibacterial effect against all the tested bacterial pathogens. The zones of inhibition against all the tested bacterial pathogens were found in the range of 8.0 to 23.2 mm, along with their respective minimum inhibitory concentration (MIC) values ranging from 62.5-1000 ig/mL. The results obtained in this study suggest that the extracts from Moringa oleifera leaf can be a source of natural antimicrobials with potential applications in pharmaceutical industry to control coliform bacteria.