Objective: To determine the surgical outcome in patients with peritonitis at tertiary care Hospital. Materials and Methods: This descriptive case series study was conducted in general surgery department of Peoples Medical Collage Hospital, Nawabshah (SBA). Study duration was two year from August 2014 to July 2016. All the patients aged more than 12 years and of both genders were included. Surgical management was done in all of the study subjects. Abdominal cavity was produced with midline incisions using grid iron as per investigations and clinical evaluation; the quantity and quality of intra-abdominal exudates were measured. Intestinal contents and pus were removed from peritoneal cavity with suction as well as by manual mopping, and full lavage was carried out with 3-5 liters of normal saline to all parts of the abdominal cavity. All the demographic data including clinical presentation and surgical outcome in terms of post-operative complications, Hospital stay and mortality were recorded via study proforma. Results: A total of 100 cases of peritonitis 75% patients were male and 25% patients were female. The mean age of patients was 36.21+12.32 years. Acute generalized abdominal pain was in all  cases, followed by fever 91.0%, vomiting 66.0%, constipation 69.0% and 2.0% patients complained of passing blood per rectum. Generalized abdominal tenderness, including rebound tenderness 90%, abdominal rigidity 83%, dehydration 88%, abdominal distention 85%, absent gut sound 70%, shifting dullness was elicited in 64% of cases and jaundice in 1.0% of cases. According to post-operative complications 20.0% patients developed Septicemia and Fecal fistula, 40.0% had wound Infection only, 9.0% patients developed wound infection and septicemia, 4.0% patients developed septicemia without any wound infection. Most of the patients had prolonged Hospital stay and overall mortality rate was 16%. Conclusion: Surgical outcome of the peritonitis resulted poor in those cases who came late and there was huge contamination of peritoneal cavity when operated, these patients developed post-operative complications i.e. wound infection, septicemia, faecal fistula and there hospital stay was longer.