In a 45-year-old female patient with Prinzmetal angina pectoris coronary angiograms and a 201thallium scintigram were performed during an ergotamine-induced episode of angina. The spontaneous and the ergotamine-induced attacks were characterized by transient ST elevation in the posterior wall ECG leads. The coronary angiogram during the attack showed spasm of the circumflex branch of the left coronary artery. In the 201thallium scintigram a large defect in myocardial thallium uptake was noticed in the posterior wall of the left ventricle. Angina and ECG abnormalities disappeared within 4 minutes. However, the scintigraphic defect disappeared only after 6 hours. The slow recovery of myocardial thallium uptake is thought to represent an alteration of the myocardium after a brief 4 minute interruption of regional coronary arterial blood flow. The diagnostic approach in patients with Prinzmetal angina is discussed.