Review of the medical records and x-ray films of 110 patients with the diagnosis "rule out abscess" showed that computerized tomography (CT) was able to correctly identify and localize a lesion in 78/79 patients. In five patients an uninfected mass was found by CT. Of 32 patients in whom no abscess was shown, only one had an abscess requiring drainage. Computerized tomography was particularly helpful in the postoperative patients in whom ultrasound examinations are difficult to perform. In many patients aspiration or drainage procedures were done at the time of examination, thus allowing us to reach immediately a final diagnosis. Based on this experience, we concluded that CT is an accurate, fast, and cost-effective examination for the diagnosis of abscesses. (JAMA 244:49-52, 1980)