Provost and Jillson reported that ethylenediamine, a stabilizer present in one widely used topical medicament, caused allergic contact dermatitis. This report documents an additional ten such patients. We also confirmed the finding that patients allergic to ethylenediamine frequently had false negative patch tests to the ethylenediamine containing medicament. Adequate patch testing requires a 1% concentration of ethylenediamine, approximately five times that found in the commercial product. Nearly all our cases were discovered as a result of routine patch testing, reemphasizing the value of a screening patch test series in the diagnosis of occult eczematous disorders.