The objectives of this study were to determine the prevalence of use of abdominal computed tomography (CT) in older ED patients with acute nontraumatic abdominal pain, describe the most common diagnostic CT findings, and determine the proportion of diagnostic CT results. This was a prospective, observational, multicenter study of 337 patients 60 years or older. History was obtained prospectively; charts were reviewed for radiographic findings, dispositions, diagnoses, and clinical course, and patients were followed up at 2 weeks for additional information. The prevalence of use of abdominal CT was 37%. The most common diagnostic findings were diverticulitis (18%), bowel obstruction (18%), nephrolithiasis (10%), and gallbladder disease (10%). Eight percent of patients had findings suggestive of neoplasm. Overall, 57% of CT results were diagnostic (95% confidence interval [CI], 49%-66%), 75% (95% CI, 63%-84%) for patients requiring acute medical or surgical intervention, and 85% (95% CI, 62%-97%) for patients requiring acute surgical intervention. CT use is highly prevalent in older ED patients with acute abdominal pain. CT results are often diagnostic, especially for patients with emergent conditions.