Aim: To determine the frequency and etiology of pericardial effusion among patients with dyspnea presenting at emergency department. Material and Methods: This retrospective observational study was carried out at emergency Department Hayatabad Medical Complex Peshawar from September 2022 to March 2023 on 120 patients. Patients having age more than 18 years presenting with dyspnea. The frequency and etiology of pericardial effusion were determined. Results: Mean age observed was 45.23±7.52 years. Pericardial effusion in our study was 15%. The most leading etiology found was para-pneumonic effusion 33.3%, renal failure 27.7%, and malignancy 22.2% while other factors 16.6%. Conclusion: we conclude that the frequency of pericardial effusion among patients presenting with dyspnea was 15%, the most common etiological factors identified were para-pneumonic effusion, renal failure and malignancy.