This study search for proper models to forecast Jakarta Composite Index (JCI) and then compare their forecasts. The stock index from strong markets, like Dow Jane Industrial Average (DJIA) and NIKKEL as well as the index from regional markets, like SEI are expected to have strong influences on JCI. More specyfcally, it is expected that SET will be able to explain the realocation of short term fund from Thailand to indonesia through capital market due to unfavour political situation in Thailand. Other than that, exchange rate is also expected to have eject on JCI movements, By using the daily data from January 3, 2005 to January 2, 2006, the stuajzfound that the proper models to be used to forecast JCI are GARCH (22) Model and ARIM4 (1,1,0) Model. The empirical results showed that the forecast from ARIM4 Model is superior to that of GARCH Model.