The objective of this investigation was to study the variations in haematological parameters of Swiss albino mice and the role of Melatonin drug against whole body irradiation with microwave radiations. For this objective mice (6-8 weeks old) from the inbred colony were selected and divided into four groups: Group I: Sham exposed, Group II: Melatonin treated, Group III: Microwave exposed, Group IV: Mel + Microwave exposed. Microwave irradiated mice were exposed with 2.45 GHz microwaves for 2 h /day for 30 consequent days. The power density during exposure was measured 0.174mW/cm2 with an average whole body specific absorption rate (SAR) 0.373 W/kg. After the above experiment blood samples of mice were collected from all mentioned groups. Microwave exposure resulted in significant decrease (P ≤ 0.001) in haemoglobin, neutrophil, packed cell volume and red blood cells. Whereas, lymphocytes, eosinophil, monocyte, platelets and white blood cells increased significantly (P ≤ 0.001) after microwave exposure in comparison to the sham exposed.LPO and Alkaline phosphatase (ALP) also increased significantly (P ≤ 0.001) after microwave exposure compared to sham exposed mice. Reduction was observed in total protein, blood sugar acid phosphatase and glutathione (GSH) level after microwave exposure compared to sham exposed mice. Under the experimental conditions tested, the data indicate that melatonin has the ability to influence the haematological parameters of Swiss albino mice
