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In order to evaluate the genetic of latent period in response with 2 races of yellow rust and general and specific combining abilities in winter wheat a half diallel was made among five cultivars. Parents and fifteen hybrids were planted in a randomized complete block design and latent period was determined with two races, namley: 134E150 and 6E18A+ in greenhouse. Owing to the high additive variance for latent period in response to race 134E150, the chance of successful selection is very high. Whereas in response to race 6E18A+ dominace variance was more important. Genetic variation of parents showed that there are specific genes in parents and those with lower latent period were dominant.