Awassi is the most widespread sheep breed of non-European origin. The breed adapts to a wide range of environmental conditions from the steppe to the highly intensive system. Performance of the breed varies according to production environment and strain, the Israeli Improved Awassi being the heaviest and producing the highest amount of milk among all Awassi populations. Efforts to genetically improve milk production yielded positive results. In Israel the phenotypic average of lactation milk production increased from 297 kg in the 1940's to over 500 kg; in the 1990's, while in Syria a selection program succeeded to increase it from 128 kg in 1974-1976 to 335 kg in 2005. In Turkey, the mean milked yield of ewes increased from 67 kg to 152 kg in a selection/outcrossing program that lasted for seven years. Although Awassi is best known for its high milk production, the breed is often used as a triple purpose sheep in most of the countries of its origin in the Middle East. Heritability estimates in different traits are within those for other populations of sheep but recent estimates for milk yield in the Improved Awassi indicated lower heritability and higher contribution of non-additive genetic effects. The Awassi sheep have been exported from its origin in east of the Mediterranean to more than 30 countries in all continents of the world. (C) 2008 Elsevier B.V. All rights reserved.