: Hydrocolloid wound dressings have been in use for nearly two decades, and have rarely caused allergic contact dermatitis. DuoDERM E (DuoDERM CGF) is a newer version of DuoDERM (Conva Tec Ltd, a division of Bristol-Myers Squibb Co, Princeton, NJ) that contains a sensitizing derivative of colophony. : We describe three patients who developed eczematous lesions under this type of wound covering. : The patients were patch tested to the European standard series, to a glues and adhesives series, and to pieces of various adhesive dressings. : The patients displayed positive patch tests to colophony and to DuoDERM E or DuoDERM CGF hydrocolloid dressings. : These dressings contain the pentaerythritol ester of hydrogenated rosin as a tackifying agent, and this substance retains the sensitizing potential of colophony. The addition of this compound is an important change that may negatively alter the good safety record of Conva Tec dressings.