Pericardial effusion is a common pathology in clinical practice. The etiology of pericardial effusion is diverse, from infectious diseases, malignancies, autoimmune diseases, chronic renal failure, to drug-related or after an invasive cardiac intervention. Clinical presentation of pericardial effusion is variable, depending on the volume of the fluid and the rate of accumulation. Clinical manifestations are dramatic if the pericardial fluid accumulates rapidly. Classical symptoms in pericardial effusion include pleuritic chest pain associated with dyspnea. In case of cardiac tamponade, orthopnea, jugular venous distension, pulsus paradoxus, hypotension, and shock appear. Transthoracic echocardiography is the gold standard investigation for the diagnosis of pericardial effusions. The echocardiographic signs of cardiac tamponade are represented by the collapse of the right atrium and right ventricle, respiratory alteration of mitral and tricuspid flow, and changes of the inferior vena cava. Management of pericardial effusion is guided by several factors, including hemodynamic impact and etiology. Pericardiocentesis guided by echocardiography is a life-saving procedure in cases of large pericardial effusions and cardiac tamponade. This is a review of the diagnosis and treatment of pericardial effusion.