Pericardial effusion may be detected as an incidental finding during echocardiography or following a diagnostic imaging study for a symptomatic patient. When a pericardial effusion is detected the first step is to assess its size, hemodynamic importance, and possible associated diseases. The more common causes of pericardial effusions include infections (viral, bacterial, especially tuberculosis), cancer, connective tissue diseases, pericardial injury syndromes, metabolic causes (i.e. hypothyroidism), myopericardial and aortic diseases. The relative frequency of different causes depends on the local epidemiology, the hospital setting and the diagnostic protocol that has been adopted. Many cases still remain idiopathic in developed countries, whereas tuberculosis is the dominant cause in developing countries. Specific testing should be performed according to clinical suspicion. The presence of elevated inflammatory markers and other criteria (chest pain, pericardial rubs, ECG changes) suggest pericarditis and management should be directed accordingly. Treatment should be targeted at the etiology as much as possible. Nevertheless, when diagnosis is still unclear, or idiopathic and inflammatory markers are elevated, empiric anti-inflammatory therapy may be worthwhile. A true isolated effusion may not require a specific treatment if the patient is asymptomatic, but large ones have a theoretical risk of progression to cardiac tamponade (up to one-third) if subacute with signs of right-sided collapse, and especially chronic (>3 months). Pericardiocentesis alone may be curative for large effusions but recurrences are also common and pericardiectomy or less invasive options (i.e. pericardial window) should be considered whenever fluid reaccumulates (especially with tamponade), becomes loculated, or biopsy material is required.