The outcome of emergency abdominal surgery in elderly patients remains unsatisfactory. We studied factors contributing to the outcome of abdominal emergency surgery in elderly patients, particularly in those aged 80 years and older. Subjects were 61 patients aged 80 years and older (group A) and 108 patients aged from 65 to 79 years (group B) who underwent emergency abdominal surgery between 1983 and 1997. Complications were significantly higher in group A than in group B, with respiratory failure the most common postoperative complication. Mortality rate within 30 days after surgery was also higher in group A (9.8%) than in group B (3.3%). Complications and mortality did not differ significantly between those with and without preexisting concomitant disease in group A. Systemic inflammatory response syndrome (SIRS) was seen in 35 patients in group A and 50 in group B. Severe complications occurred in 62.5% of group A with preoperative SIRS. Mortality in those with SIRS was significantly higher than those without. SIRS is thus a feasible predictor of poor outcome in patients aged 80 years and older who have emergency abdominal surgery and in those aged from 65 to 79 years. Patients with SIRS should initially receive minimal treatment whenever possible, rather than be overtreated, until their conditions stabilize.