The present study evaluated to assess genetic variability in performance traits, Blood Parameters and immune competence by using biotechnological methods on two Egyptian broiler lines Cairo-B2 and Random breed control (RBC). A total of two thousand chicks, from the ninth generation from lines, were reared in four replicated rooms under the same conditions until 8 weeks of age. Live body weight was determined weekly for Cairo-B2 and Random breed control (RBC) until 8 weeks, Blood samples were collected at 4 weeks of age from 20 chicks from each line to determined Triiodothyronine(T3), thyroxine (T4), total protein (TP), total lipids (TL), hematocrit (Ht), and Insulin-like Growth Factor-1 (IGF-1), The primary immune response of 30 chicks per line to Sheep red blood cells (SRBC) antigens was injected at 4 weeks and repeated at 6 weeks of age. 40 chicks from each line were slaughtered to determined carcass characteristics, the Cairo-B2 line had significantly higher than RBC line in body weight, carcass, breast meat, neck and wings weights.  The results were the RBC line had significantly higher T3 and IGF-1 than the Cairo-B2 line and there was no significant difference in T4, TP, TL and Ht between the lines. The RBC line had higher antibodies titers to SRBC than the Cairo-B2 line that was shown in each injection. We are concluded that selection for high body weight over many generations can negatively effect on the immune response and carcass weight.