PURPOSE: The purpose of this study was to spectrophotometrically evaluate the influence of porcelain layer thickness and substructure. MATERIALS AND METHODS: Four groups of porcelain specimens (metal and ceramic substructure) was prepared for analysis. Color parameters were measured with spectrophotometer and color difference (DeltaE*) were calculated. T-test and one-way ANOVA test were used to find out significant difference and Tukey test was used to identify where the difference ware. RESULTS: Increasing the thickness of porcelain decreased values (P < 0.05). Increasing the thickness of porcelain on ceramic substructure decreased the a* (P < 0.05) but, the b* were not statistically different. Total color difference (DeltaE*) were below 1 when the difference of porcelain thickness were 0.5 mm. CONCLUSION: The thickness of porcelain are the factor effecting on color. This study will help the color are controlled by changing the thickness of porcelain clinically.