Coronary artery dissection (CD) is a rare cause of acute myocardial ischemia. It is often diagnosed by invasive coronary angiography, which is the principal diagnostic tool and gold standard in the diagnosis and triage of patients with CD. More recently, electrocardiogram-gated multidetector computerized tomography has emerged as a complementary imaging tool primarily for follow-up purposes. To our knowledge, this is the first published report of the primary diagnosis and dynamic cine interrogation of a left main CD using retrospective electrocardiogram-gated multidetector computerized tomography, which was not disclosed on invasive coronary angiography.