Stress-induced cardiomyopathy (SIC) is a novel syndrome with a substantial morbidity and mortality rate. It has become an important differential diagnosis in patients with acute chest pain. The characteristic hallmark of SIC is a development of extensive but reversible left ventricular dysfunction which may cause fulminant heart failure, cardiogenic shock and literally heart rupture leading to death. In spite of the rapidly increasing number of patients, a lot of elementary facts are unknown in regard to epidemiology, pathophysiology, prognosis and optimal treatment. Substantial evidence has been accumulated in the literature during the last couple of years that renders the SIC diagnostic criteria proposed from Mayo Clinic obsolete. In this paper we offer a new set of clinical criteria which we believe better defines the SIC syndrome. Based on the data from the newly established national SIC registry in Sweden, we estimate that as many as 1500-2000 patients annually develop the advanced stage of SIC in our country. It is plausible to assume that the true incidence of SIC is generally much higher if we accept the fact that subclinical and milder forms of SIC in the population do not come to medical attention and that SIC is often mistaken for an acute coronary syndrome. SIC may therefore be the most common form of non-ischemic cardiomyopathy in Sweden and elsewhere.