Dissertation (MMED General Surgery)Background: Anastomotic leak following gastrointestinal surgery is the most post-operative complication that causes significant morbidity and mortality. Its burden is high in low and middle income countries likes Tanzania with lack of supportive data on incidence of Anastomotic leak, predictors and outcome. Objective: This study aims to determine the predictors and early outcomes of anastomotic leak among patients who underwent primary bowel resection and anastomosis at Iringa Regional Referral Hospital in Tanzania. Methodology: This was a hospital based retrospective study involving patients underwent primary bowel resection and anastomosis at Iringa Regional Referral hospital. It included data from January 2015 to December 2018. Demographic, indications, preoperative, intraoperative and postoperative data were abstracted using questionnaire sheet. Data analysis was done with Statistical Package for Social Science (SPSS 23.0). Numerical data was summarized using median and interquartile range (IQR) while categorical data was summarized using frequency and proportions. Logistic regression analysis was run to identify the predictors for anastomotic leak. Findings were presented using tables and figures. Results: A total of 335 cases were analyzed for which 19% had anastomotic leak after gastrointestinal anastomosis. The median age was 50 years old with Interquartile Range (IQR) 36 to 62 years old. The predictors that had statistical significant included diabetes mellitus [AOR=2.38, 95%CI: 1.01-5.43], Tuberculosis [AOR=13.13, 95%CI: 2.18-79.04], high American Association for Anesthesiology (ASA) score [AOR=2.39, 95%CI: 1.15-4.97], surgery done by residents and registrars [AOR=2.47, 95%CI: 1.22-5.00] and longer duration of surgery more than 2 hours remained very significant predictor for anastomotic leak [AOR=3.23, 95%CI: 1.51-6.90]. Conclusion: Anastomotic leak was high from the site and remains common problem after gastrointestinal surgery. Co-morbidity illness such as diabetes mellitus; tuberculosis and high American Association for Anesthesiology score, cadre of the surgeon and longer duration of surgery were the most significant independent predictors for anastomotic leak. Morbidity and mortality due to anastomotic leak ware high among patients underwent primary anastomosis.