Purpose: An increasing number of inlay cavities is restored with tooth-colored materials, especially ceramics are cemented with resin cements. The comonomer TEGDMA and other monomers Bis-GMA and UDMA have been identified as the main compounds released from polymerized resin cements into aqueous media. The present investigation was conducted to clarify the leaching behavior of the monomers of dual polymerized resin cement. Material and methods: Ten freshly extracted caries and restoration free molar teeth were used in this study. Standardized Class I preparations were prepared in all teeth. Lithium disilicate based (IPS Empress Esthetic) ceramic inlays were cemented with dual polymerized resin cement (Variolink II). After cementation, specimens were stored in 75% ethanol solution. High-performance liquid chromatography (HPLC) was used to analyze the amounts of three monomers in the solution (after 10 min, 1 h, 24 h, 3, 7,14, and 21 days). Two-way ANOVA and Tukey HSD tests were used to evaluate the results (p < 0.05). Results: There were statistically significant differences among the amounts of the monomers (p < 0.01) and also among time periods (p < 0.01). While the TEGDMA resulted in significantly higher amount than Bis-GMA and UDMA, there were no statistically significant differences between amounts of Bis-GMA, UDMA (p = 0.06). The cumulative amount of monomers was the highest after 21 days (p < 0.01). Conclusion: In the case of resin cement, leaching of TEGDMA was the highest and the cumulative amount of leaching monomers from resin cement was influenced by the time. (C) 2008 Wiley Periodicals, Inc.