The goal of this study is to investigate the causal relationship between financial development and economic growth in Gulf Cooperation Council (GCC) countries, i.e. Bahrain, Oman, Kuwait, Qatar, United Arab Emirates and Saudi Arabia, over the period 1980-2012. We employ panel unit root tests, and Error Correction Model and cointegration techniques to detect long-run and short-run causalities between the variables used in our study. The overall empirical results reveal that the financial sector development contributes significantly to economic growth in the GCC countries. Our results could be of great interest for policymakers since the financial sector could play a crucial role in lowering the dependency of the governments to oil revenues and could contribute significantly to spur economic growth.