Aim: The aim of the present study was to assess and compare the clinical performance of post-operative sensitivity among two types of bulk-fill resin-based composite in class II posterior restorations using visual analog scale (VAS). Materials & Methods: Twenty patients having proximal caries were arbitrarily selected and divided into two groups according to type of the restorative materials. Fourty class II cavities were prepared and restored with Sonicfill2 bulk fill resin composite, (Kerr Crop., Orange, CA, USA) (n = 20) and Fill Up dual cure bulk fill resin composite, (Coltene, Whaledent, Switzerland) (n =20). POS of restored teeth was assessed with a standardized cold test and air stimulus by air blow from air syringe. Patient responses were assessed at an interval of 24 h, 1month, 3 months, and 6 months using a Visual Analog Scale (VAS). Statistical analysis was performed using paired t-test, independent t- hoc test using SPSS program version 21 (SPSS Inc., Chicago, IL., USA). Results: The statistical analysis showed after 3 months as well as 6 months, there was no statistically significant disagreement between the two bulk fill resin composite types. However, after 24 h as well as 1 month POS was seen a less notable in Fill up bulk fill resin composite. Finally, in comparing between the two bulk fill resin composites no statistically significant disagreement was recorded. Conclusion: The postoperative sensitivity is related to many factors as the type of resin composite used, the procedure of cavity preparation and the placement technique of the resin composite.