This study looked into the grill chickens' Parquetina nigrescens leaf extract (PNLE) antioxidant capacity. Parquetina nigrescens leaves that were still fresh were collected from Ilishan-Remo in Ogun State, Nigeria. The experiment was carried out in the Babcock University Farmhouse's chicken department in Ilishan-Remo, Ogun State, Nigeria. After gathering the leaves and combining them with 50g of the leaves in 1000ml of water, the extract was produced. A total of 200-day-old Ross broiler chicks were divided into five groups at random and given different amounts of PNLE in 500 millilitres of water (0, 0.2, 0.4, 0.6, and 0.8 millilitres). The experiment lasted for 42 days. The design of the experiment was completely randomized design. Data was collected on performance, hematology, serum biochemical and antioxidant parameters, and temperature and humidity were monitored regularly. Data were subjected to a one-way analysis of variance (p<0.05). There was no significant difference (p>0.05) in performance characteristics. There was a significant difference (p<0.05) in malonaldehyde with the 0ml PNLE group having the highest value (3.5U/L X 109). There was a significant difference in catalase and superoxide dismutase with the 0.4ml PNLE group having significantly highest (p<0.05) values. Glutathione peroxidase was considerably (p<0.05) impacted by PNLE administration. Total protein, albumin, globulin, glucose, cholesterol, triglycerides, urea, aspartate transaminase, and alanine transaminase were not substantially (p>0.05) affected by PNLE delivery. The control group had considerably lower (p<0.05) values for alanine phosphatase and red blood cell counts, and significantly higher (p<0.05) values for creatinine. It is concluded that PNLE has good antioxidant potential thus improving the health status of broiler chickens.