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Leaf rust caused by Puccinia triticina Eriks., is one of the main diseases of wheat (Triticum aestivum L.) in Egypt, causing up to 50% of yield losses. Genetic resistance is the most economic and effective means of reducing yield losses caused by the disease. However, breeding genotypes for disease resistance is a continuous process and plant breeders need to add new effective sources to their breeding materials. Among 42 Egyptian wheat varieties screened for leaf rust resistance, only 9 varieties (Sakha94, Giza168, Gemmiza9, Gemmiza10, Gemmiza11, Sids12, Sids13, Misr1 and Misr2) exhibited seedling and adult plant resistance during 2010/11 and 2011/12 growing seasons. Out of 41 monogenic line (Lr genes) tested, only 13 Lr genes (Lr9, Lr10, Lr11, Lr16, Lr18, Lr19, Lr26, Lr27, Lr29, Lr30, Lr34, Lr42 and Lr46) exhibited seedling resistance while, 9 Lr genes (Lr19, Lr20, Lr21, Lr24, Lr29, Lr30, Lr32, Lr34 and Lr44) showed adult plant resistance at both growing seasons. This result may add a depth of their resistance to be exploited as good sources of resistance. Partial resistance traits of wheat seedlings were present in 12 varieties (Sids12, Misr2, Sakha94, Misr1, Sids13, Giza168, Gemmiza9, Sids7, Beniswef4, Sakha93, Gemmiza11 and Sids6), recording the longest incubation and latent period. However, 10 varieties (Sakha8, Sakha93, Giza144, Giza155, Giza156, Giza157, Sids4, Sids5, Sids8 and Beniswef4) were marked as having high level of partial resistance of adult plant, recording ACI less than 20%, AUDPC less than 332.5 and r-value less than 0.101. The highest significant loss percentages were found in susceptible wheat cultivars i.e. Gemmiza7, Sakha61 and Giza164 (12.24%, 12.10% and 9.08%, respectively). However, insignificant loss percentages were found in resistant cultivars i.e. Giza168 (1.87%), Misr2 (2.44%) Sakha94 (2.46%). Inverse relation was present between the disease level and grain yield. Cultivating of resistant cultivars such as Misr2, Giza168 and Sakha94 is recommended to escape heavy yield losses wreaked by the leaf rust disease.