The Authors have presented the clinical, hemodynamic, coronary arteriographic and left ventriculographic findings, and the results of medical and surgical treatment in 17 patients with main left coronary artery disease (MLCA). Clinically MLCA disease can only be suspected, in the AA's experience, if a patient presents with markedly positive exercise stress test and/or unstable angina. Coronary arteriography and left ventriculography confirmed the high incidence of associated 2-3 vessel coronary artery disease and of severe left ventricular segmental wall motion abnormalities. Surgical results and clinical follow up have indicated a better prognosis and quality of life in operated, compared with medically treated patients. Our experience confirms that MLCA disease is a dangerous clinical entity, which, when suspected, must be managed with proper indication to coronary arteriography and aorto-coronary bypass surgery, both associated, in our experience, with acceptable morbidity and mortality and good long term results.