Although the elderly account for a disproportionate number of patients with intraabdominal infections, few studies have compared these patients with younger patients in terms of presentation and outcome. Therefore, we conducted a retrospective cohort study of 131 patients at an urban university hospital that included 88 patients (67%) < or = 65 years of age and 43 (33%) > 65 years of age, all of whom had culture-proven intraabdominal infections. Geriatric patients presented more frequently without the typical symptoms and signs of abdominal pain, nausea and vomiting, diarrhea, and fever and had symptoms for a longer period before presentation. Diagnosis on admission was more often unknown or considered to be of an extraabdominal nature for the elderly patients, and sources of infection were more commonly biliary or pancreatic. Mortality was not significantly different between the groups, but length of stay and duration until normalization of body temperature were longer for the older patients. We concluded that elderly patients with intraabdominal infections frequently present atypically and have a more-protracted course of illness than their younger counterparts.