Intra-abdominal infection continues to pose a significant threat to critically ill patients in the year 2000. A review of the current literature reveals that despite remarkable developments in critical care medicine and extensive study of patients with tertiary peritonitis, the associated mortality rate remains nearly 30%. Progress has been limited by the difficulty of comparing heterogeneous patient populations, groups that manifest a host of comorbid, potentially confounding illnesses. Additionally, debate persists regarding the definitions of secondary and tertiary peritonitis, resulting in varied study inclusion criteria, and further complicating data analysis and interpretation. Scoring systems developed to identify those patients at risk for progression to tertiary peritonitis, the more chronic, lethal form of intra-abdominal infection associated with multisystem organ failure, reflect the current emphasis in the literature on the importance of early diagnosis and early intervention. This has led to a renewed interest in conservative, data-dependent surgical management employing radiographic and microbiologic evidence to guide therapy.