Isocyanates are widely used in the manufacturing of rigid and flexible foams, fibers, and coatings such as paints, varnishes, and elastomers but are rarely reported as contact sensitizers. The aliphatic diisocyanate dicyclohexylmethane-4,4'-diisocyanate (DMDI) is known to be a strong cutaneous sensitizer. We report a 27-year-old woman who developed a severe eczematous eruption on the arms, trunk, and abdomen within 2 weeks of employment at a company using the product Chem-Dec 808 isocyanate (containing 40-70% weight per weight DMDI). Patch testing was performed with the North American screening series, an isocyanate series, and 1% Chem-Dec 808 isocyanate. At day 7, a +++ reaction to Chem-Dec 808 isocyanate and a ++ reaction to the aromatic isocyanate diphenylmethane-4,4'-diisocyanate were observed. DMDI has strong sensitizing potential and requires rigorous safety monitoring in the workplace.