Abstract: Multiple drug resistant Escherichia coli isolated from Rajshahi metropolis, which were resistant against ampicillin, tetracycline, chloramphenicol, erythromycin, kanamycin, streptomycin and nalidixic acid at 90, 70, 45, 45, 35, 30 and 10% respectively. Moreover, plasmid DNAs having molecular weight of 5.0 to 8.1 MD and molecular size of 28.4 to 39.0 kb has been isolated from these drug resistant mutants.