Objectives: The aim of this in vitro study was to examine the effect of different curing lights and modes on the color stability of adhesive resin cement material. Methods: A conventional halogen light and a light emitting diode unit were used to polymerize resin cement with catalyst. A pressable ceramic block (10 mm in diameter, 2 mm in height) was used as an interface between the polymerizing light tip and resin cement. Colorimetric values of the specimens before and after polymerization were measured using a spectrophotometer (Easy Shade). This in vitro study evaluated the color stability of commercially available resin cements under accelerated conditions. The CIE L*a*b color system was used for the determination of the color difference. Differences between measurements were calculated as ΔE*ab. Repeated measurements analysis of variance (ANOVA) was used to analyze the data for significant differences. The Tukey HSD test and paired two-tailed tests were used to perform multiple comparisons. Results: The type of polymerizing light had a significant effect on L*,a* and b* values and ΔE ,where as the effect of polymerization mode was not significant.-Halogen light resulted in more color changes ΔE than LED light. Aging resulted in color changes in ΔE, These were above the perceivable value (ΔE < 2.5). Conclusions: The results of this in vitro study suggest that light polymerization of the resin cement (Variolink II) used in this study is an important factor for the color of the definitive restoration and should be considered during shade selection and fabrication.