The prevalence and genetic basis of resistance of multi-drug resistant (MDR) S typhi strains from an urban paediatric population was determined. Blood cultures performed on 109 cases of suspected typhoid fever yielded 30(27.5 % ) S typhi isolates. Of these, 20(67 %) S typhi isolates were resistant to the common antimicrobials used in Bangladesh, eg, chloramphenicol, ampicillin, cotrimoxazole, streptomycin and tetracycline, while 6(20%) isolates were resistant only to streptomycin. However, all the isolates were sensitive to fluquinolones and cephalosporins. Molecular analysis demonstrated that all MDR strains possessed a single large transferable 98 MDal plasmid.