Aim: The study aims to measure the surface roughness (Ra) of three resin composites subsequent to polishing with diamond-impregnated polishing paste. Materials and Methods: Sixty specimens (10 mm × 2 mm) were prepared in metal molds using three nanocomposites: GC Sculpt, Filtek Z350 XT, and Tetric N Ceram. Specimens were then subjected to baseline roughening with #600 grit sandpaper and were polished with DirectDia paste according to the manufacturer's instructions. After polishing, the Ra of resin composites of all the specimens was measured using profilometer and the surfaces were seen under scanning electron microscope. Results: Tetric N Ceram specimens were significantly smoother and had the least R a value compared to other groups. Conclusion: Among the three resin composites tested, Tetric N Ceram exhibited the least R a value owing to the small size of inorganic filler particles.