Objectives: the aim of the study was to evaluate the surface roughness of Bulk-Fill resin composite when compared to Nano-filled incremental resin composite in both acidic and alkaline media after 24 hours and 3 months.Methods: A total number of 42 sound human premolars. The occlusal surface of each tooth was grounded flat. Specimens were randomly divided into two main groups according to the material used whether Xtra-fil or Grandio. Specimens were subjected to PH challenge. The surface roughness was evaluated using profilometer. A Three-way ANOVA, followed by Tukey’s post-hoc test was used.Results: An insignificant increase in the surface roughness of the Xtra-fill more than the Grandio and an insignificant increase in surface roughness of alkaline medium compared to other media.Conclusion: The recently designed resin composites tend to behave similarly under different conditions.