The glycidyloxy compounds constitute an important group of chemicals used extensively in the formulation of epoxy resin systems employed in coatings, electronics, structural composites, and adhesives. Although extensive toxicological data are available on glycidyloxy compounds, use and understanding of the data have been hampered by two major problems: (1) proper identification and complexity of the epoxy systems in question, and (2) absence of meaningful classification of epoxy materials. This paper provides a classification scheme with CAS numbers and reviews the mammalian toxicology of the most common glycidyloxy derivatives used in epoxy resin systems based on both published and proprietary information. Although the toxicity of many of the glycidyloxy compounds used in epoxy resin systems can be characterized as low, the diversity of compounds found within this group precludes broad generalizations for the class. This comprehensive account should facilitate a clearer understanding of the potential health effects and allow for easier comparison among compounds containing the glycidyloxy moiety.