This study was conducted to investigate the effects of adding raw garlic in the diets on certain hematological and serum biochemistry of broiler chicken. Total of (40) birds (one day old) were used for this study. The birds divided randomly and equally into (4) treatment groups which fed on one of the following for 56 days: group (1) was fed on 10% raw garlic with basal diet, group (2) was fed on 5% raw garlic with basal diet, group (3) fed on basal diet and antibiotic (Ampicillin) which was added to the drinking water and group (4) fed on basal diet only (control group)The results showed that there were no significant alteration in PCV and RBCs in the group which fed on 10% raw garlic compared with the control one, however these group showed significant (p<0.01) reduction in HbC, MCV, MCHC and MCH. The addition of 5% raw garlic to the diet of bird caused significant (p<0.01) reduction in MCH and MCV only where as other haematological parameters (PCV, RBCs count, HbC and MCHC) have not affected significantly compared with the control group. The group which received antibiotic showed significant reduction (p<0.01) in HbC and MCHC. On the other hand, all treatment groups have not altered the total WBC and differential leucocytic counts. The coagulation time was prolonged significantly in groups that fed on both levels of garlic. The biochemical analysis of the serum has not any significant changes in serum total protein and glucose levels in all treatment groups. However, the serum cholesterol levels of birds fed on both levels of garlic (10% and/or 5%) reduced significantly (p<0.01) as compared with the control group