An experiment was carried out to investigate the effects of using garlic (Allium sativum) as an additive on haematological profile in broiler chicken production. The study was carried out at Livestock Investigation Department (L.I.D) of the National Veterinary Research Institute (N.V.R.I), Vom. The experiment lasted eight weeks. A total of 144, one day-old broiler chicks of Arbor acre breed were used for the study in a completely randomized design (CRD). The birds were allotted into four (4) dietary treatments with each having three (3) replicates. Processed and ground garlic was added into the drinking water of each treatment at 0g, 3g, 6g and 9g per liter of drinking water representing treatments 1, 2, 3 and 4, respectively. The result of haematological analysis showed that all the parameters were significantly (P<0.05) different across the dietary treatments. The white blood cells in T4 (12.13) which is higher than 10.21, 8.65 and 7,68 respectively. This indicates that the health of the birds was challenged in T4 even though they are all within the normal range (Merck's Manual, 1998). Packed cell volume (PCV) level of T4 was the Lowest among the dietary treatments. It can therefore be concluded that garlic used as an additive in drinking water showed no deleterious effect in haematological parameters of broiler chickens rather it boosted their immunity.