Purpose: This study was directed to evaluate the microleakage of class V composite restoration after fluoride Iontophoresis application on tooth surface. Materials and Methods :60 freshly extracted human non carious premolar teeth were used box-shaped Class V cavities (4x2x2 mm) were prepared on the gingival one third of the tooth with occlusal margin in enamel and gingival margin in cementum half of the teeth received fluoride Iontophoresis application (FI), while the other half were not received any treatment (NF). Teeth were restored with Z250 resin composite and Kalore resin composite. The specimens stored for one month, three months and six months in distilled water at 37o C in an incubator. After storage time, specimens were immersed in dye of silver nitrate for 12 hrs. The tooth restoration interface was investigated under Scanning Electron Microscope (SEM). Results: no significant difference in microleakage of both restorations. Lower leakage score for the fluoridated group than none fluoridated one. Microleakage levels were higher in teeth occlusally than cervically. Conclusion: Microleakage is adversely affected by Fluoride iontophoresis.