Dissertation (MMed Internal Medicine)Background: Diarrhea is still a major cause of disease burden worldwide. Very limited information is available about the burden, etiology and factors associated with bacterial diarrhea in individual aged 5 years and above in Tanzania. Therefore this study was conducted to fill this gap. Methods: Across sectional analytical study was conducted among individuals 5 years and above presenting with diarrhea at Dodoma Regional Referral Hospital and St Gemma’s Hospital from February 2019 to June 2019. Convenient sampling was used to obtain eligible participants. Fresh stool specimens were collected for analysis. Standard bacteriological procedures were employed to isolate the bacteria and assess the drug sensitivity patterns of the isolates, and SPSS version 21 used to analyze data. Associations between variables were tested by univariate model. The factor(s) with p value less than 0.05 was considered as statistically significant and was subjected to multivariate analysis to adjust the effect of other confounders.. Results: A total of 362 participants were recruited into the study. The prevalence of bacterial diarrhea was 7.2%. The most common isolate was Shigella spp. 18(69.2%), followed by Salmonella spp 5 (19.2%), and E.coli 3(11.6%). High levels of sensitivity were observed for Ciprofloxacin and Gentamycin (80 - 100%). The factors which independently showed significant association with bacterial diarrhea were bloody diarrhea, insufficient water supply and no water treatment. Conclusion: The prevalence of bacterial diarrhea was 7.2%. Shigella and Salmonella spp were the most common isolates. Ciprofloxacin and Gentamycin were most effective drugs. Bloody diaarhea, insufficient water supply and no water treatment were the factors independently associated with bacterial diarrhea. Implementation of water and sanitation interventions is therefore important in prevention and control of bacterial diarrhea.