Background and Aim: Determining the best restorative material to decrease micro leakage in class V restorations is of great importance in operative dentistry. The aim of this in-vitro study was to evaluate the micro leakage of silorane-based COMPOSITES compared to low shrinkage methacrylate-based COMPOSITES in class V restorations.Materials and Methods: In this in vitro study, class V cavities were prepared on the buccal and lingual surfaces of 24 human premolars and molars (48 cavities). The specimens were divided into four groups of 6 (12 cavities) as follows: group 1 (LS System Adhesive, Primer & Bond + Filtek P90), group 2 (Kalore-GC+ Clearfil SE bond), group 3 (Clearfil SE bond + Grandio) and group4 (Clearfil SE bond + Aelite LS Posterior). All the specimens were thermo cycled for 2000 cycles (5-50oC).The teeth were then immersed in 0.5% basic fuchsin dye for 24 hours at 37oC, sectioned and observed under stereomicroscope. Data were analyzed using Kruskal-Wallis and Wilcoxon tests at a P<0.05 level of significance.Results: There were no significant differences in micro leakage among the four groups at the occlusal margin (P>0.05). But, there were statistically significant differences in micro leakage between Silorane and Aelite at the gingival margin (P<0.05).Statistically significant differences were also found in micro leakage between occlusal and gingival margins (except for Kalore and Silorane) (P>0.05)Conclusion: Silorane was not superior to the conventional low shrinkage methacrylate-based COMPOSITES except for A elite in terms of micro leakage.