The aim of this study is to examine the effect of different finishing and polishing systems on the surface roughness, microhardness and microleakage of a nano-hybrid composite. The effect of four different finishing and polishing systems (Mylar-strip, Diamond finishing bur, Sof-lex disc, PoGo) were evaluated on a nanohybrid composite (Ceram-X mono, Denstply). The surface roughness was measured by profilometer, microhardness was measured by Vicker's icrohardness tester. For microleakage evaluation, class V cavities (3x4x2 mm) were prepared at cemento-enamel junction of 60 third molars. Teeth were thermocycled 500 times (5-55°C) and immersed in 0.5% basic-fuchsin for 24-hours and evaluated. The two-way ANOVA and Posthoc tests were used for surface roughness, One-way-variance-analysis and Posthoc tests were used for microhardness and microleakage was analyzed by Kruskal-Wallis and Mann-Whitney-U tests. Measured surface roughness scores listed according to the techniques as; PoGo＜Mylarstrip= Sof-lex＜Diamond bur (p=0.000), microhardness scores as; Mylar-strip=diamond bur＜Sof- Lex＜PoGo (p=0.010), microleakage scores as; PoGo＜diamond bur=Mylar-strip＜Sof-Lex (p=0.004). PoGo was found as the most successful group regarding the investigated properties. Conclusions: The findings revealed that finishing and polishing techniques have a significant effect on the surface roughness, surface hardness and marginal sealing ability of composite restorations.