Abstract: A fifty-six (56) days feeding trial was conducted in a completely randomized design to determine the haematological and serum biochemical characteristics of Hacco cocks fed Cocoabean Shell (CBS) supplemented with vitamin E and beta-glucan. Forty (40) cockerels (aged twenty-five weeks) were used. Treatment diets comprised T1 (control) (i.e. 0% CBS); T2 (20% CBS); T3 (20% CBS + Vitamin E) and T4 (20% CBS + Beta-glucan). The haematological parameters determined were Packed Cell Volume (PCV), haemoglobin concentration (Hb), Red Blood Cell Count (RBC) and White Blood Cell Count (WBC). Others included the WBC differential counts-polymorphs, lymphocytes, monocytes and eosinophils. The serum biochemical parameters determined were serum enzyme activities namely Spartate Amino Transferase (AST), Alanine Amino Trasferase (ALT) and alkaline phosphatase. Other parameters were total protein albumin, globulin and cholesterol. Treatment had significant (p<0.05) effect on PCV, RBC, WBC and polymorphs, while Hb, lymphocytes, monocytes and eosinophils were not significantly (p>0.05) affected by the treatment. Cocks that were fed CBS and CBS + Beta-glucan had similar PCV, RBC and WBC and polymorphs with the control group, while those that were fed CBS + vitamin E had lower values for PCV, RBC and polymorphs than the control group. The groups fed CBS + vitamin E had higher (p<0.05) WBC values than other groups. All the serum parameters determined were not significantly affected by dietary treatment. It was concluded that 20% CBS in diets of cocks did not show adverse effect on the blood parameters of the cocks. When supplemented with β-glucan, there was no adverse effect either. However, when supplemented with vitamin E, some haematological parameters were adversely affected.