We systematically investigated risk factors for typhoid fever in Kamalapur, a poor urban area of Bangladesh, to inform targeted public health measures for its control. We interviewed patients with typhoid fever and two age-matched controls per case about exposures during the 14 days before the onset of illness. The municipal water supply was used by all 41 cases and 81of 82 controls. In multivariate analysis, drinking unboiled water at home was a significant risk factor [adjusted odds ratio (aOR) 12·1, 95% CI 2·2–65·6]. Twenty-three (56%) cases and 21 (26%) controls reported that water from the primary source was foul-smelling (aOR 7·4, 95% CI 2·1–25·4). Eating papaya was associated with illness (aOR 5·2, 95% CI 1·2–22·2). Using a latrine for defecation was significantly protective (aOR 0·1, 95% CI 0·02–0·9). Improved chlorination of the municipal water supply or disinfecting drinking water at the household level may dramatically reduce the risk of typhoid fever in Kamalapur. The protective effect of using latrines, particularly among young children, should be investigated further.