Records were reviewed from 83 cases to determine the main causes and clinical significance of feline pericardial effusion. The most common causes included hypertrophic cardiomyopathy with congestive heart failure, neoplasia, and systemic infection. Most cases had concurrent or secondary pleural effusion or pulmonary edema, with clinical signs of respiratory disease. However, several cases appeared to be affected solely by pericardial effusion rather than pulmonary pathology. Feline pericardial effusion remains an infrequent diagnosis, but its clinical relevance and association with severe cardiac and extracardiac disease warrant diagnostic evaluation.