The study evaluates the effect of economy policy uncertainty of US on gulf cooperation council (GCC) countries' stock market returns. The GCC countries are Saudi Arabia, Qatar, UAE, Kuwait, Bahrain and Oman. Granger Causality Tests (GCT) was done primarily to evaluate if economy policy uncertainty granger cause on GCC stock market returns. The analysis established that oil prices granger cause stock market returns for Saudi Arabia, Kuwait and UAE; the same is not true on changes in economic policy uncertainty of US cause on the stock market returns. Changes in economy policy uncertainty in US granger causes on stock market returns of Bahrain. On the other hand, economy policy uncertainty in US does not cause stock market returns in Qatar, UAE, Kuwait and Saudi Arabia. Vector Autoregression (VAR) analysis establishes that economy policy uncertainty in US negatively responds to the stock market returns of the GCC countries.