The Arabian horse ignites imagination throughout the world. Populations of this breed exist in many countries, and recent genetic work has examined the diversity and ancestry of a few of these populations in isolation. Here we explore seven different populations of Arabians represented by 682 horses. Three of these are Middle Eastern populations from near the historical origin of the breed, including Syrian, Persian, and Saudi Arabian. The remaining Western populations are found in Europe (the Shagya-Arabian and Polish-Arabian) and America (American-Arabian). Analysis of genetic structure was carried out using 15 microsatellite loci. Genetic distances, AMOVA, factorial correspondence analysis and a Bayesian method were applied. The results consistently show higher level of diversity within the Middle Eastern populations than the Western populations. The Western Arabian populations were the main source of among populations variation. Genetic differentiation was not strong among all Middle Eastern populations, but all American-Arabians showed differentiation from Middle Eastern populations and were somewhat uniform among themselves. Here, we explore the diversities of many different populations of Arabian horses, and find that populations not from the Middle East have noticeably lower levels of diversity, which may adversely affect the health of these populations.