Peritonitis is the inflammation of peritoneum of clinical emergency importance either in operation room or intensive care unit. Peritonitis is divided into primary, secondary, and tertiary. Primary peritonitis or spontaneous peritonitis is arises in the absence of an identifiable anatomical causes and has a low incidence on surgical intensive care units. Secondary peritonitis (SP) is the commonest peritonitis which is defined as an infection of the peritoneal cavity resulting from perforation, anastomotic disruption, ischemic necrosis, or other injuries of the gastrointestinal tract. Tertiary peritonitis can be defined as the persistence or recurrence of intra-abdominal infection with multiple organ failure and a systemic inflammatory response in an immune compromised host that develops after what was thought to be a effective attempt at primary source control. The management of tertiary peritonitis should include the provision of appropriate physiologic support, the administration of antimicrobial therapy, and operation or intervention to control the source of contamination and to decrease the bacterial load. Moreover, two crucial components must be present, which include the time period, which is 48 hours, and there must be successful surgical source control. Moreover, tertiary peritonitis remains a vital cause of hospital death mainly among patients with associated risk factors.