Objectives: The aim of this study was to evaluate the cytotoxicity of four low-shrink composites with new monomer technology on the bovine dental pulp-derived cells (bDPCs). Materials and methods: Ten samples were prepared for each group composites, and the samples were immersed in 7 mL of culture medium for 72 h at 37°C to extract residual monomer or cytotoxic substances. The culture medium containing the material extracts was sterile filtered for use on the cell cultures. Materials were incubated in medium with serum for 72 h. bDPCs were maintained in a medium with serum. A real-time cell analyzer was used to evaluate cell survival. After seeding 200 mL of the cell suspensions into the wells (10,000 cells/well) of the E-plate 96, bDPCs were treated with bioactive components released by the composite materials (1:1 and 1:2 dilutions) and monitored every 15 min for 50 h. Results: According to analysis of variance, there were significant differences between the cell indexes of the control and GC kalore (p < 0.05) and BiscoReflexions (p < 0.001) groups for the 1:1 dilutions at 25 h.When evaluated at 50 h, 1:1 dilutions of GC Kalore (p < 0.01) and Bisco Reflexions (p < 0.001) reduced cell survival significantly. Conclusions: Although composites resins are being advanced, their cytotoxic effects have been proceeding till this time.However, twoof the fourmaterials tested significantly reduced cell viability when compared with control.