The high cost of conventional feed ingredients for livestock and competition between man and his animals, necessitate the need for alternative and under-utilized plant materials in poultry nutrition. However, in doing so, it is important to ensure that such plant materials are not deleterious to the animals. This research therefore examines the effect of bush buck (Gongronema latifolia) leaf extracts as dietary supplements on haematological and serum biochemical parameters of broiler chickens. Fresh leaves (6kg) of bush buck (Gongronema latifolia) were after rinsing with de-ionized water air-dried for ten (10) days under room temperature and were ground in a hammer mill to pass through 0.5mm sieve. It was thereafter dissolved in de-ionized warm water (40oC) at 1kg per 5 litres of water and was left to settle for 1 hour before decanting the supernatant. One hundred and ninety-two (192) broiler chicks, after brooding for two weeks were divided into six (6) dietary treatment groups of thirty two (32) birds each. Birds on dietary treatment 1, had no vitamin/mineral supplement in water, while dietary treatment 2 birds had supplemental commercial vitamin/mineral premix (vitalyte extra). Dietary treatments 3, 4, 5 and 6 had Gongronema latifolia leaf warm water extract in the following ratios; 25, 50, 75, and 100ml/litre of water respectively. The vitalyte extra was administered (5g/l) once a week while the birds had access to feed and water/GLLE ad libitum. On the last day of the experiment, blood samples were collected from the birds for haematological analysis. All the assayed parameters such as packed cell volume (PCV), white blood cell (WBC), red blood cell (RBC), heterophil (H), lymphocyte (L), monocyte (M), eosinophil (E), basophil (B), haemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC) and mean corpuscular haemoglobin (MCH) were significantly (P<0.05) influenced by the dietary treatments. The analyzed serum biochemical indices such as total protein, albumin, globulin, creatinine, uric acid, aspartate aminotransferase, alanine aminotransferase, sodium and potassium were generally better in the 25ml/l GLLE. Glucose was significantly reduced in the vitalyte treatment while total cholesterol, high and low density lipoprotein were least in the 50ml/l GLLE treatment. In conclusion, the results above revealed that the Gongronema latifolia leaf warm (40oC) water extract of 50ml/l was safer and supported better health and wellbeing of the broiler chickens. This shows that Gongronema latifolia leaf warm (40oC) water extract could be used to wholly replace the conventional vitamins and minerals (vitalyte extra) in broiler diets without any adverse effect on growth and health performance of the birds.