Introduction Preserving marginal integrity of dental restorations is a challenge for dentists. Bond failure and loss of marginal seal may lead to microleakage, with subsequent possibility of marginal discoloration, postoperative sensitivity, recurrent caries or even restorative failure The aim of study The current study was conducted to investigate the influence of ultrasonic scaling on microleakage under composite restorations bonded with 3 different adhesives. Materials and Methods Sixty standerdized class V cavities were prepared in extracted human molars that were divided in to three groups, according to the type of applied adhesive, as follows: Group A: Fuji Bond LC, Glass ionomer (GI) adhesive, Group B: Clearfill S3 Bond, Self-Etch (SE) adhesive and Group C: OptiBond FL, Etch and Rinse (ER) adhesive. After cavity preparation and composite filling, teeth of each group were further divided into scaled and un-scaled subgroups. Teeth were sectioned buccolingually and the gingival margins of the teeth were evaluated and scored for dye penetration to check the microleakage. Results Scaling caused a significant increase in microleakage scores of SE adhesive. On the other hand, both ER adhesive and GI adhesive showed insignificant change in microleakage scores after exposure to the ultrasonic scaling.Self- Etch adhesive showed the highest mean rank microleakage value (13.7), while GI adhesive had the lowest mean rank microleakage value (12.9) in the scaled group. Significant difference between the scaled (mean rank 13.7) and un-scaled (mean rank 7.3) subgroups was found only with SE adhesive (p = 0.007). On the other hand, insignificant differences (p = 0.06) were noticed between the two subgroups of GI and ER adhesive. Conclusion Ultrasonic scaling caused significant increase in microleakage of self-etch adhesive bonded restorations. While GI and ER adhevies bonded restorations revealed more resistance to the effect of ultrasonic scaling