Several in vitro studies have shown increased intracellular level of reactive oxygen species (ROS) after exposure to 2-hydroxyethyl methacrylate (HEMA), a commonly used monomer in resin-based dental materials. This study aimed to investigate the initial changes of the proteome in a human monocyte cell line after exposure to HEMA by using Stable Isotope Labelling with Amino Acids in Cell culture (SILAC).