The main objective of this research is to investigate factors influencing the growth of Islamic banks’ assets in Indonesia. Firstly, this research adopts Granger Causality Test under Vector Auto-Regression (VAR) method and secondly, it adopts Vector Error Correction Model (VECM) through Impulse Response Function (IRF) and Forecasted Error Variance Decomposition (FEVD) analyses. The period of the research is from March 2004 to December 2009 and the data are time-series data that are cited from SEKI-BI, SPS, SPI, BPS and annual reports. The finding of Granger Causality Test in Indonesian Islamic banks concludes that industrial production does not have causal relationship with asset growth. This is due to the size of industrial production, which is too big to cause the asset growth and the size of Islamic banks’ asset, which is too small (2.5%) to cause the industrial production in the country. Conclusion of VECM model through its IRF and FEVD is that inflation and interest rate are major variables that negatively affect the asset growth while industrial production, human capital and office branch and channeling are variables that contribute positive impact to the asset growth. Although the impact is insignificant, human capital and office branch and channeling promise long-term positive impact to asset growth.