In a recent Nature Genetics Letter entitled 'Common genetic variants account for differences in gene expression among ethnic groups', Spielman et al. estimate the number of genes differentially expressed between individuals of European (CEU) and Asian (ASN) ancestry and suggest that these differences can be accounted for by measured genetic variants. We recently performed a similar study comparing differences in gene expression among individuals of European and Yoruban ancestry. Given the scientific, medical and societal implications of this research area, it is important for the scientific community to carefully revisit and critically evaluate the conclusions of such studies. To this end, we have reanalyzed the data in Spielman et al. to provide a common basis for comparison with our study. In doing so, we found that important issues arise about the accuracy of their results.