The purpose of this study was to determine the sensitivity and specificity of computed tomography (CT) without administration of oral contrast in confirming suspected acute appendicitis. One hundred seventy-three patient studies were retrieved by a computer-generated search for the word "appendicitis" in radiology reports. Patients presenting to the emergency department over an 8-month period were examined for acute abdominal pain or suspected acute appendicitis. IV-contrast-enhanced CT scans of the abdomen and pelvis were obtained without oral or rectal contrast. Criteria for diagnosis of acute appendicitis included a dilated appendix (>6 mm), periappendiceal inflammation, or abscess. Final diagnoses were established with surgical/clinical follow-up, histopathological analysis or both. The standard time (1 h) for the administration of oral contrast prior to the CT scan was eliminated. Fifty-nine CT diagnoses were made of acute appendicitis, 56 of which were histologically verified and three of which resulted in another diagnosis. One hundred fourteen CT diagnoses were negative for appendicitis. This corresponds to a sensitivity of 100% and specificity of 97%, a positive predictive value of 95%, and a negative predictive value of 100%. CT with IV contrast is sensitive and specific for the confirmation or exclusion of acute appendicitis. By eliminating the time required to administer oral contrast, the diagnosis might be made more rapidly.