Cardiac tamponade is a vital emergency. It occurs when the accumulation of intra-pericardial fluid exceeds the pericardial adaptation capacity. Pericardial pressure is equalized with that of cardiac cavities and severe heart failure occurs, most often rapidly. Several clinical presentations are possible. The diagnosis is based on the assessment of pericardial effusion and its impact on the heart by echocardiography. Supportive treatments have limited effectiveness. The only emergency treatment is drainage of the pericardium by direct puncture or by surgical approach.