Purpose: The objective of this study was to evaluate –not only the translucency but also the colors- of two different brands of nano-filled resin composites. Materials and methods: Forty composite resin specimens (twenty from each material) in the form of discs (8 mm diameter) with various thicknesses (1.5, 2, 2.5 and 3 mm) were fabricated of TeticEvoCeram and 3M ESPE Filtek Z350 XT according to manufacturer’s instructions. The CIELAB parameters (L*, a* and b*) of composite discs were evaluated on backings of black, white and the material itself to calculate the translucency parameter (TP) and the color differences (ΔE*). Regression analysis using Two-way Analysis of Variance (ANOVA) was used for studying effect of specimen type, thickness and their interactions on means color difference (ΔE), translucency parameter (TP), translucency difference (ΔTP) and the color co-ordinates L* a* b* values. Results: The specimen type, thickness and the interaction of the two variables had a statistically significant effect on means (ΔE) and (TP). 3mm thickness discs had the lowest (TP) value and 1.5mm thickness discs had the highest (TP) value. Conclusions: The translucency decreased as the thickness of the specimens increased.