Pericardial effusion is a common result of pericardial injury caused by a variety of processes. Pericardial effusion leads to an increase in intrapericardial pressure, which can compromise the filling of cardiac chambers and results in decreased cardiac output – a hemodynamic and clinical syndrome of cardiac tamponade. Diagnostic work-up of pericardial effusion and tamponade is focused on revealing the etiology and assessing the hemodynamic consequence. Echocardiography has a crucial role among imaging methods. Therapy differs according to the etiology and the presence of tamponade, when it is targeted to evacuation of the effusion and to diminishing of its effect on cardiac output.