| Long - Run Underperformance is a common IPO phenomenon in the capital markets and have been chosen as a research topic in many countries. The purpose of this research is to prove Long-Run Underperformance phenomenon in Indonesia's IPOs and to determine factors that influence Long-Run Performance. The samples of this research are companies doing IPO at Indonesia Stock Exchange in period of 2000-2010. Long - Run Performance which is measured by Buy and Hold Abnormal Return (BHAR) is dependent variable. Independent variables of this research are : Firm Age, Company Size, Issue Size, dan Earning Per Share. The relation between dependent variable and Independent variables is tested by multiple regression model. Regression analysis shows that Long-Run Underperformance phenomenon occurs in Indonesia's IPOs. The analysis also shows that Company Size have a positive and significant influence on Long-Run Performance but Firm Age, Issue Size, and Earning Per Share do not have a significant influence on Long-Run Performance |