Dissertation (MMED Surgery)Background: Peritonitis is a common surgical condition which can occur either primarily or secondarily to other underlying pathologies including post operation. Studies show that the major causes of peritonitis are bowels perforations, perforated appendix, volvulus and strangulated bowel. Objective: This study aimed at describing the patterns, and early treatment outcomes of patients with peritonitis at Dodoma Regional Referral Hospital. Methods: This was prospective cross sectional hospital based study which included all patients admitted with the clinical features of peritonitis for seven months from 1/10/2015 to 30/4/2016. The study was conducted in surgical wards of Dodoma Regional Referral Hospital which is located in Dodoma Region, central part of Tanzania. Results: A total number of 66 patients with generalized peritonitis were involved in the study. Of these, 23 (34.85%) were females and 43 (65.15%) were males. Perforation was found to be the commonest cause accounting for 51 (77.3%) and was slightly higher in males than female patients. Typhoid fever was the leading cause of perforations leading to peritonitis in 12 patients (18.18% ) followed by abdominal trauma 9 patients (13.64%) while the least causes were inflammatory bowel disease and idiopathic 2 patients each (6.06% ). Conclusion: Generalized peritonitis was found to be a common problem at Dodoma Referral Regional Hospital and in the developing countries as a whole. It seems to affects individuals mostly from low social economic class of which males were affected more than females. Mortality and morbidity found to be high