Spiral (helical) computed tomography (CT) involves continuous patient translation during x-ray source rotation and data acquisition. As a result, a volume data set is obtained in a relatively short period of time. For chest or abdominal scanning, an entire examination can be completed in a single breath hold of the patient or in several successive short breath holds. The data volume may be viewed as conventional transaxial images or with multiplanar and three-dimensional methods. The authors review the technologic aspects of spiral CT, as well as its advantages, limitations, and current clinical applications.