Objective : This study was performed to evaluate the etiology, clinical outcome and prognosis of patient with large PE treated by echo-guided pericardiocentesis. Method : We reviewed 101 consecutive patient who underwent echo-guided pericardiocentesis due to large pericardial effusion with or without cardiac tamponade for last 10 years. We analyzed their etiology, mortality rate, and life expectancy according to the etiology. Results : Mortality rate of PE according to their etiology was as follows (table 1). Among neoplastic PE, lung cancer (43%) and breast cancer (18%) were the most common malignancy. Iatrogenic or traumatic PE were related with percutaneous coronary intervention, open heart surgery, and incidental chest trauma. During the follow-up period after percutaneous pericardiocentesis, 55% of patients had died from complications of their underlying disease. Risk of death was significantly higher among neoplastic PE than non-neoplstic PE by Kaplan-Meier survival curve (p<0.001). The frequency, effusion cytologic detection rate and mean life expectancy of neoplastic PE was about 43 % and 5.5 months. Conclusions : (1) Neoplasm, tuberculosis, and uremia were the most common causes of large PE. (2) The prognosis of large PE is related to patients' underlying disease. Neoplastic PE had the worst prognosis, in other hand tuberculsis, thyroid PE and connective tissue disease had relatively better prognosis.