Single-photon emission computed tomography (SPECT) is frequently used with myocardial perfusion imaging in the assessment of patients with known or suspected coronary artery disease. The susceptibility of SPECT imaging to artifact, especially that caused by patient motion, has long been recognized. We report a characteristic artifact of patient motion, which we have termed the "hurricane sign" because of its similarity to the National Weather Service Symbol for a hurricane. This artifact is caused by varying contributions of different portions of the heart during image acquisition and their misalignment produced by patient motion.