Abstract: The aim of this preliminary investigation was to assess the probable effects of microwave exposure on Hematological parameters of RBC (Red Blood Cell), PCV (Packed Cell Volume) and Hb (Hemoglobin) in rats. For this study 80 Sprague Dawley rats were exposed to 2450 MHZ microwave field for a period of one year. The experiment groups were divided to 5 groups, each 16 (8 males and 8 female), 4 for treatment and one, for control (D, E, F, G and H).The incident power density of the first two experiment groups was 1 mW m-2 and for next two groups, was 10 mW cm-2. The daily exposure time was 5 min for groups F and G and 30 min for groups, D and F. The animals in control group (H) were under normal condition without any microwave exposure. In the end of the study the blood samples were taken from the heart of animals under ether anesthesia and determination of blood parameters were performed by cell counter auto analyzer. According to the statistical results, the level of RBC in male groups of F and G and percentage of PCV in female and male groups of F and content of Hb, in female groups of F, were significantly increased in comparison to the control group and variation of results in other groups were not significant.