Objectives: To evaluate the effect of essential oils (EO) of Mint and Anise with organic acid on broiler performance. A total of 384 hatched broiler chicks were randomly allocated to 6 treatments with four replicates each. The experimental treatments were included a corn-soybean based diet as control, diet containing Mint EO (150 ppm), diet containing Anise EO (150ppm), diet containing a commercial organic acid (Orgacids® 3 g/kg), diet containing a combination of EO’s of Mint and Anise (150ppm of each) and a diet containing a combination of Orgacids (3g/kg) and Anise (150ppm of each). Materials & Methods: Blood samples were obtained after killing broilers on 21 days. The blood samples were allowed to clot at room temperature and centrifuged for 15 minutes at 3000rpm. HI was determined for NDV in serum samples. Blood samples were centrifuged for 3 minutes at 15000 rpm, haematocrit values were determined. CBC differentiated has done and heterophil /lymphocyte ratio was measured. Results & Conclusion: The result showed that addition of organic acid and essential oils of Mint and Anise had no significant effect on red blood cells count and haematocrit values in broilers at 1-21 days of age when compared with control (p>0.05). Essential oil of Mint, combination of Mint and Anise EOs and combination of organic acid and essential oils significantly (p<0.05) increased the haemagglutination inhibition test (HI) against Newcastle disease virus in comparison with control. The combination of organic acid and essential oils had no significant effect on heterophil /lymphocyte ratio. However, essential oil of Anise significantly (p<0.05) increased the heterophil /lymphocyte ratio in comparison to Orgacids. In conclusion, the results of this experiment showed that addition of Mint and Anise essential oils to the diet had no effect on red blood cells and haematocrit values in first 21 days of age of broiler chickens, and addition of organic acid and its combination with essential oi
