The aim of this study was to compare the effect of various polishing techniques and overglazing on the surface roughness of Vita Mark™II blocks (70 specimens) IPS Empress CAD™blocks (70 specimens) and IPS e.max CAD™blocks (70 specimens). First, all specimens were ground with 50-micron diamond burs to simulate surface derived from Cerec milling system. The surface roughness was measured with a profilometer. Seventy blocks of each type of ceramic were divided into 7 groups (10 blocks each). Groups 1 and 2 were polished with Astropol™, groups 3 and 4 with SofLex™disc, groups 5 and 6 with OptraFine™system for 20 and 40 strokes respectively. Group 7 was overglazed. The mean values of average surface roughness (Ra) were compared using 3-way, 2-way and 1-way ANOVA, and Post Hoc Scheffe test (α=0.05). In Vita Mark™II groups, the lowest Ra was overglazed group. No significant difference in the mean surface roughness values was found between ceramic polished with OptraFine™system 20, 40 strokes, Astropol™ 40 strokes and SofLex™disc 40 strokes, which Ra were inferior to overglazed group. In IPS Empress CAD™groups, the lowest Ra was overglazed group. No significant difference in the mean surface roughness values was found between ceramic polished with OptraFine™system 20, 40 strokes, SofLex™disc 20, 40 strokes, which Ra were inferior to overglazed group. In IPS e.max CAD™group, the lowest Ra was overglazed group, no significant difference in the mean surface roughness values was found between ceramic polished with SofLex™disc 40 strokes and OptraFine™system 40 strokes, which Ra were inferior to overglazed group. From this study the smoothest surface for all ceramic was found in the overglazed group. The proper polishing method for Vita Mark™II was to polish with OptraFine™20, 40 strokes, SofLex™disc 40 strokes, Astropol™ 40 strokes, IPS Empress CAD™ with OptraFine™20, 40 strokes, SofLex™disc 20, 40 strokes, and IPS e.max CAD™ with SofLex™disc 40 strokes and OptraFine™system 40 strokes.