This study on the effects of graded doses of aqueous extract of Garcina kola seeds on growth performance and haematological response of broiler chicks was carried out to investigate the effects of different dosage regimen of the extract on growth performance and haematological indices of body homeostasis. A total of 30 broilers Chicks of anak 2000 strain were assigned into 3 treatment groups of ten birds each. Group A (control) received 0.0ml of aqueous extract of Garcina kola seeds / kg body mass of bird. Group B and C received1.0 and 2.0 ml extract of Garcina kola seeds per kilogram body mass of birds. The growth performance indices of feed consumption, live body mass were taken on weekly basis while dressed body mass and selected organs mass were taken at the end of experiment. Uncoagulated blood was collected 12 h post treatment. The result obtained showed a significant (p<0.05) dose dependent reduction in growth performance whereas there were no significant (p<0.05) changes in haematological indices of body homeostasis except for percentage parked cell volume, haemoglobin concentration, eosinophils, lymphocyte and monocyte (agranulocyte) counts which revealed a significant (p<0.05) increase at both doses. The above findings imply that aqueous extract of Garcinia kola seeds should not be used above 0.5ml (100mg/kg) body mass even for medicinal purposes in broilers.