Purpose: The aim of this study was to evaluate resin-based posterior restorative materials by comparing the release of BPA, TEGDMA, HEMA, UDMA, and Bis-GMA monomers at 1 hour, 3 days and 1 month. Materials and Methods: Five different materials were used in this study: Cerasmart (CS), Gradia-Plus Indirect (GI), G-ænial Posterior (GP), Formlabs 3D- Permanent Crown (FPC), and SonicFill-3 (SF). A total of 90 specimens, 8 x 8 x 2 mm3 in size were prepared from all the materials. The specimens were immersed in 75% ethanol / 25% water solution in an incubator for 1 hour, 3 days, and 1 month, after which the solutions were analyzed using high-performance liquid chromatography (HPLC). For the comparisons of data with normal distribution among the five different materials, Repeated Measures ANOVA followed by the Bonferroni post-hoc test was applied (a=0.05). Results: Except for BPA release in the FPC material, all other materials exhibited an increasing release of monomers over time (P < .001).At all the measured time points, the material with the lowest monomer release was CS, while the highest release was observed in GP. The GI material exhibited the statistically significant highest release of BPA, TEGDMA and BisGMA (P < .001), while the highest UDMA and HEMA release was observed in the GP material (P < .001). Conclusion: The highest monomer release was observed for UDMA (0.8%) from the GP material at the end of one month. However, the monomer release from all examined materials remained well below the clinically acceptable range (1.5% – 5%).