Aims and Objectives : Bulk Fill composites possess specific characteristics, including enhanced flowability to achieve consistent adaptation to the cavity preparation. The present study assessed microleakage of bulk fill composites. Materials & Methods: 45 extracted mandibular molar teeth were divided into three groups of 15 teeth each. Group I teeth were restored using SonicFill Bulk Fill composite, group II with Tetric Evo Ceram and group III with X-tra fil and evaluated for microleakage at the occlusal and cervical walls. Results: The mean microleakage along occlusal wall in group I, II and III had score 0 seen in 7, 2 and 2 teeth, score 1 seen in 3, 5 and 2 teeth , score 2 seen in 2, 2 and 3 teeth and score 3 seen in 3, 6 and 8 teeth respectively. Mean microleakage along cervical level in group I, II and III had score 0 seen in 2,1 and 0 teeth, score1 seen in 3,2 and 0 teeth, score 2 seen in 5,3 and 3 teeth and score 3 seen in 5, 9 and 12 teeth. The difference was significant (P< 0.05). Conclusion: SonicFill Bulk Fill composite showed lesser microleakage at both cervical and occlusal walls. Key words: Sonic Bulk Fill composite, Microleakage, Occlusal wall