Purpose: To search the pattern of diagnoses in nonagenarians undergoing emergency abdominal surgery between January 2009 and December 2013 in two hospitals. To test the hypothesis that pre-hospital functional status is an effective criterion for predicting postoperative mortality in nonagenarians after emergency abdominal surgery. Methods: The study is an observational study on 157 patients. Patients were identified from the operation database and perioperative data were extracted as prospectively information supplied by retrospective data from patient electronic files. The primary endpoints were short, middle and long-term mortality and the secondary endpoint was to identify preoperative factors associated with postoperative mortality. Results: The most frequent reason for operation was intestinal obstruction. Overall mortality in the cohort was 34% (n = 54) after 30 days and 54% (n = 84) after 1 year. Amongst patients developing a serious complication (classified as Clavien Dindo class III or greater) after surgery (n = 45) the mortality was 80% (n = 36) after 30 days and 89% (n = 40) after 1 year. In multivariate analysis, a high American Association of Anesthesiologists class (ASA) and a high Performance Status (PS) class (low performance) were significant predictors of post-operative mortality. Conclusion: Our data support pre-admission functional status for predicting postoperative mortality after emergency abdominal surgery in nonagenarians