Spiral computed tomography is a new noninvasive diagnostic test for pulmonary embolism. The method provides tomographic images of the thorax in the axial plane, which depict the thoracic wall, the mediastinum, the lungs, and the pulmonary vessels. Thrombotic emboli in the vessels are seen as intraluminal filling defects in the contrast-enhanced pulmonary arteries. The physical principles of spiral computed tomography and several technical considerations concerning image quality will be briefly discussed. The accuracy of spiral computed tomography in the detection of pulmonary embolism is discussed by way of an overview of published validation and clinical outcome studies encompassing spiral computed tomography and the diagnosis of pulmonary embolism.