The present study aimed to evaluate the effect of in ovo injection with Folic acid and adding ascorbic acid (VC) into the drinking water on growth performance, carcass yield, some blood biochemical changes and immune response of broiler chicks. A total of 150 eggs were randomly divided into three groups. The 1^st one has no treatment (control) , while the 2^nd was  in ovo injected with 0.1 ml distilled water/egg  (Sh - group) . The third one was given  injected by folic acid 10% ( 0.1 ml/egg ). Feeding and flock management were done in accordance with commercial practices. The results indicated that chicks hatched from eggs treated with folic acid or folic acid and  then given VC in the drinking water had  higher body weight,  carcass (%), breast muscle yield and lymphoid organs weight than other treatments. The visceral organs of the birds likewise increased. Plasma  concentration of total lipid, cholesterol, triglycerides and LDL were  significantly decreased by both folic acid injection and VC addition to drinking water .  Addition of  VC  was  effective  on increasing intestinal total count of bacteria while, decreasing intestinal count of Escherichia coli. It could be successfully used as alternative to antibiotic growth promoters as a tool of controlling intestinal pathogenic bacteria.