This study uses a panel KSS test by Nuri Ucar and Tolga Omay (2009), with a Fourier function based on the sequential panel selection method (SPSM) procedure proposed by Georgios Chortareas and George Kapetanios (2009) to test the efficiency of REIT markets in 16 countries from 28 March 2008 to 27 June 2011. A Fourier approximation often captures the behavior of an unknown break, and testing for a unit root increases its power to do so. Moreover, SPSM can determine the mix of I(0) and I(1) series in a panel setting to clarify how many and which are random walk processes. Our empirical results demonstrate that REIT markets are efficient in all sampled countries except the UK. Our results imply that investors in countries with efficient REIT markets can adopt more passive portfolio strategies.