There is mixed support for the hypothesis that the banking sector is a channel for economic growth. While most studies on economic growth in Gulf Cooperation Council (GCC) countries have not distinguished between conventional banks and Islamic banks, this study contributes to the empirical literature by comparing the respective impacts of Islamic banks and commercial banks on economic growth among GCC countries during the period 2001–2009, bringing out policy implications. The main result of panel data regressions is that both conventional and Islamic banks have fuelled economic growth, with the latter having a more significant impact. These results contradict the findings of some single-country studies that have examined the impact of Islamic banking on economic growth.