Wheat (T. aestivum) is a major staple food crop in modern societies, providing 20% of the caloric intake globally. The leading wheat-producing nations are China, India, and the United States, which annually produce 100, 70, and 64 million tons, respectively. Increasing modernization and industrialization on a global scale have changed the diets of developing countries, leading to increased consumption of grains and an increased global demand. In Egypt, it occupies about 3 million feddans which yield approximately 8 million tons. Wheat is liable to be attacked by many diseases particularly rust diseases. Under field conditions, this investigation included studying the effectiveness of stem rust resistance genes, the performance of some local wheat varieties as well as identification of adult plant resistance gene (s) of stem rust in these previous varieties under disease stress in the field. The results obtained revealed the following: - 1. Effectiveness of stem rust resistance gene (s) (Sr,s) in the adult  plant stage: According to the response of forty-six monogenic lines for stem rust resistance (Sr,s), data obtained revealed that the stem rust resistance gene (s) that were effective during the three growing seasons were Sr 2 Comp., Sr 24, Sr 25, Sr 26, Sr 28, Sr 31, Sr 32, Sr 33, Sr 34, Sr 36, Sr 37, Sr 38, Sr 39 and Sr 40. Thus, these lines should be considered in breeding for resistance. While Sr 7a, Sr 7b, Sr 8a, Sr 8b, Sr 9a, Sr 9b, Sr 9d, Sr 9e, Sr 9g, Sr 10, Sr 12, Sr 13, Sr 14, Sr 16, Sr 17, Sr 18, Sr 19, Sr 20, Sr 21, Sr 22, Sr 23, Sr 27, Sr 30, Sr 35, Sr Tmp. and Sr McN. exhibited high levels of stem rust severity and susceptible reaction during the three growing seasons of the study. Moreover, the third group included Sr genes with variable reactions during the three growing seasons i.e. Sr 5, Sr 6, Sr 11, Sr 15, Sr 29, and Sr Wld-1. 2. Evaluation of some wheat varieties against stem rust under natural conditions.