BACKGROUND Epoxy resin compounds (ERC) include a large number of sensitizing chemicals such as epoxy resins (ER), hardeners (curing agents), and reactive diluents. Allergic contact dermatitis (ACD) caused by ERCS is often occupational. METHODS We report a patient, sensitized to a hardener of a two-component epoxy paint. Three conventional patch test sessions were performed to diagnose the causative chemical. We also review the literature on sensitizing epoxy-resin hardeners. RESULTS A 47-year-old nonatopic woman developed dermatitis from a two-component epoxy paint. Patch testing with epoxy resin was negative, but 2,4,6-tris(dimethylaminomethyl)phenol (tris-DMP), used in the paint hardener, induced an allergic patch test reaction. We also review briefly other epoxy hardeners that have caused allergic dermatitis, including: (1) aliphatic polyamines, e.g., ethylenediamine, diethylenetriamine, triethylenetetramine, 3-dimethylaminopropylamine, and trimethylhexamethylenediamine; (2) cycloaliphatic polyamines, e.g., isophoronediamine and 3,3'-dimethyl-4,4-diaminodicyclohexylmethane; (3) aromatic amines, such as 4,4'-diaminodiphenylmethane, m-phenylene diamine, and 1,3-xylylene diamine; (4) dicyanodiamide; (5) triglycidyl isocyanurate, an epoxy compound that may be used as an epoxy-resin hardener; and (6) additives in epoxy accelerators, such as hexavalent chromate. CONCLUSIONS No one chemical can be used to screen for sensitization to the many different epoxy hardeners. Extensive patch testing may be required to reveal the hardener that has caused the allergy. The hardener, 2,4,6-tris-(dimethylaminomethyl)phenol (tris-DMP), is a new sensitizer. To verify ACD caused by tris-DMP, patch-testing at 1% in petrolatum is suggested.