Background and Objectives: With the advances that are being made in many areas of medicine, the surgeon must be familiar with infectious diseases of the peritoneal cavity which has increased in severity and complexity. Objective of my study was to study the validity of a scoring system, presently being studied worldwide along the following lines: 1. Analysis of various causes of acute peritonitis with respect to morbidity and mortality. 2. Mannheim peritonitis index scoring system as a predictor of prognosis in acute peritonitis. 3. To assess the role of laparoscopy in acute peritonitis.

Methods: All patients above the age of 18 year diagnosed with acute peritonitis and admitted to MVJMC & RH, Surgical Ward or who develop features of peritonitis due to various causes excluding obstetric and gynecological causes and those secondary to dialysis, admitted between the period November 2014 to July 2016.

Results: In our study duodenal perforation formed 65.4% of cases and mortality attributed to it was only 0.9%. Overall mortality was 4.5%. MPI score predicted both morbidity and mortality accurately, patients with MPI score < 26 had no mortality but who above 26, mortality was around 20% which is statistically significant (p < 0.001).

Interpretation and Conclusion: MPI score predicted mortality & morbidity well. It helped in 1. Determining morbidity pre operatively. 2. Duration of hospital stay. 3. Surgery can be safely done irrespective of scores. 4. Duration of peritonitis < 24 hour and its outcome on post operative complications. 5. Score above 20, managed well in ICU where adequate monitoring and facilities available and its impact on prognosis.