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The arrival of a patient with chest pain syndrome (precordial) to the emergency represents a diagnostic challenge for the physician. Around 6 million persons are seen each year at the Emergency units in the USA. More than half of the patients are admitted for their cardiac evaluation. Its cardiac origin is confirmed in 10 to 15%, and about 15% of them develop myocardial infarction. However, 5 to 10% of patients are dismissed and develop myocardial infarction during the next 48 h. The diagnosis of the infarct is inadvertent and/or patients is not hospitalized in 2 to 8%. The mortality rate is duplicated in none hospitalized patients. Frequently, a conservative observation conduct and/or diagnostic expectation is taken, with the consequent saturation of the intensive care unit that looses its critical character and avoids quick mobilization of the patient with an increase in costs. The clinical judgment, a meticulous clinical history, and careful physical examination play a key role in the differential diagnosis of the precordial pain syndrome; however, pain can be atypical, absent or manifest as an equivalent of pain, which does not exclude the diagnosis of myocardial infarction or ischemia. Likewise, chest pain in the presence of a normal conventional ECG at rest, non-diagnostic or with minimal variations, does not rule out the possibility of a coronary obstruction and does not mean that the pain is not of coronary origin. Other characteristics of the ECG, such as T wave and ST segment alterations, bundle branch block (BBB), LV hypertrophy, interpretation discrepancies, can pose doubts or mistakes in the diagnosis. Although its diagnostic information is essential, other non-invasive laboratory tests are needed, such as the treadmill stress ECG, serial bioenzymatic markers, and myocardial perfusion scintigraphy (SPECT and Gated-SPECT) at rest or under physical or pharmacologic stress. The advantages and disadvantages of the stress ECG, the echocardiography, magnetic resonance and PET are mentioned. The advantages of the SPECT and Gated-SPECT in the diagnosis and prognosis are: 1) great diagnostic objectivity; 2) high sensitivity and specificity; 3) diagnosis does not depend on evolution time of the ischemia and/or infarction, since SPECT diagnoses the initial primary modifications of ischemia; 4) diagnosis is achieved within the established limit of time, in less than 4 to 6 hours. The designed protocols allow to obtain the diagnosis between 30 min and 1:30 h; 5) assesses the myocardium at risk; 6) stratifies the risk and prognosis; 7) defines the site and 8) the involved coronary artery(les); 9) provides the functional significance of the anatomic obstruction; 10) quantifies the ventricular function, i.e., ejection fraction, systolic and diastolic volumes, systolic thickening, ventricular failure signs; 11) provides three-dimensional visualization of the mobility of the left ventricular wall; 12) diagnoses simultaneously the associated presence of ischemia and/or infarction of the right ventricle; 13) its high negative predictive value allows to dismiss immediately and with a great safety margin those patients in whom SPECT revealed normal perfusion; 14) costs are reduced without adversely compromising the safety of the patients. We describe the algorithm used as guideline for the early diagnosis in the presence or absence of ischemic heart disease in the patient with precordial or chest pain syndrome with normal or non-diagnostic ECG at arrival to the emergency ward. It is necessary to modified the clinical educational patterns and to revaluate the advantages and limitations of the clinical history, physical exploration, as well as of the conventional ECG at rest and other diagnostic methods used specifically in relation to the chest pain syndrome with a normal or non diagnostic conventional ECG. SPECT and Gated-SPECT scintigraphy is considered as the best individual and isolated non-invasive test for the diagnostic solution of the precordial syndrome at the Emergency Unit.