The chicken Major Histocompatibility Complex (MHC) is closely related to resistance to several diseases. Moreover, selection for genetic resistance to diseases is a critical goal in the broiler breeding companies, which should be carefully balanced with different economic traits, including live body weight (LBW) and meat yield. The microsatellite marker LEI0258 is used to evaluate the effect of selection for 12 generations for high LBW at 6 weeks of age (LBW6) with natural selection against Marek disease (MD) on genetic component associated with resistance to MD and Newcastle diseases (ND) in local broiler breeders, Cairo B-2 line, compared to commercial broiler breeder line (AA line). Results indicated that, Cairo B-2 line had lower carcass parts with higher internal organs percentages compared to AA line. In addition, there was a positive association between 473 bp allele of LEI0258 with regard to LBW6 and carcass traits in two lines. Moreover, LEI0258 alleles 357 bp and 295 bp were present with high content in Cairo B-2 line only, which increased the genetic resistance to Marek's disease and increased the humoral immune response against ND vaccination in Cairo B-2 line compared to AA line. The correlations between these valuable productive traits and LEI0258 microsatellite will effectively assist the selection process by applying Marker-Assisted Selection in Cairo B-2 line breeding program in the future.