The effects of aqueous extract of Parquetina nigrescens leaves on the haematological and serum biochemical parameters of broilers were investigated at dose of 400 g/4litres of water. 120 broilers were grouped into 4 treatments, 3 replicate of 10 broilers each. Treatment 1(control) was administered normal water and vaccination/medication when necessary. The other groups were administered extracts via: Treatment 2 – 400g aqueous extract/4liters of water for 2days weekly, Treatment 3 – 400g aqueous extract/4liters of water for 3days weekly and Treatment 4 – 400g aqueous extract/4liters of water for 5 days weekly. The result shows there was a significant different (P<0.05) in the lymphocyte and basophils percentage. Treatment 3 has the highest lymphocyte value (34.50 %) while treatment 1 has the least value (25.24 %). The control group has the highest basophils (3.86 %) percentage and it is significantly (P<0.05) different from other treatments. There was a significant difference (p<0.05) in the heterophils, esinophils, lymphocyte, RBC count, hemoglobin and PCV percentage of the broiler chicken. Treatment 1 has the highest value of PCV, hemoglobin, RBC count and lymphocyte respectively while treatment 3 has the least value. Treatment 1 has the least value (45.68 %) of heterophils while treatment 3 has the highest value (59.58 %). The results on serum profile of the broiler at Starter phase showed a significant (p<0.05) decrease in the values of Creatinine as the days of administration of the test herb increases. The control group has the highest value (132.75 µmol/l) of creatinine while treatment 3 has the least value (18.43 µmol/l). The 400g level of the aqueous extract of Parquetina nigrescens in 4litres of drinking water of broiler chickens for 3 days in a week were found to be most suitable in terms health and wellbeing of the chickens because it did not compromise their biochemical and physiological status