Thirteen patients presenting with contact dermatitis and having positive results of closed patch tests to 1% ethylenediamine dihydrochloride solution were observed in a 4-month period. A mixture containing triamcinolone acetonide, neomycin, gramicidin, and nystatin (Mycolog Cream) which contains ethylenediamine as a stabilizer had been recently used by 12 of these patients. Only 4 of the 10 patients who were patch tested to Mycolog Cream had a positive response. Eleven of the patients presented with a history of rapid onset of a patchy eczematous generalized eruption. Two patients given aminophylline, which contains theophylline and ethylenediamine, developed an exacerbation of their generalized patchy eczematous eruptions. In all patients, the dermatitis cleared following the use of 1% hydro-cortisone cream and avoidance of Mycolog Cream. This illustrates the difficulty in evaluating a potential contactant, the industrial sources of which are reputed to be many, but unknown, and which is present in a popular topical medication together with 2 unknown contactants and triamcinolone.