Purpose: The purpose of this investigation was to study, the effect of microwave on experimental orthodontic tooth movements in 21 male Spraque-Dawley rats at 75 days old.Methods: In this study, the compare of Control group (n:7,no application), I.experimental group(n:7) in which orthodontic forces were aplied without microwave exposure. II.experimental group (n:7) in which orthodotic forces and microwave were applied. Microwave exposure was 2.65 mV/cm 2 for one hour daily for 13 days. On 3 t h day of exposure period orthodontic appliance was applied in this groupand macroscobic measurments were done every 24 hours. Rats were sacrified under ether anaesthetized on the 13 t h day than their premaxilla were removed enbloc and routine histological studies have been done were evaluated light microscope.Results: The proliferation of peridontal cells, vascular activation and interstitiel hemorrhage were observed. The findings were little more severe in II.experimental group than I.experimental group. The amount of orthodontic tooth movement increased statistically significat only on 1 s t day (P[lt ]0.001).Conclusions: It was concluded that microwave was not effect in the rate of orthodontic tooth movement over all experimental period.