Three instances of sensitivity to bithionol have been seen in the past year. A girl, aged 5, developed a flare-up of dermatitis on the chin, following the use of an antiseptic cream. Blind patch tests disclosed a three-plus reaction to the sample containing bithionol, which reproduced the initial patch test response to the antiseptic cream. The latter also contained hexachlorophene. This produced a one-plus patch test reaction. Recurrence of the dermatitis followed the use of a chap lotion containing this chemical. A male, aged 51, developed a weeping dermatitis of the forehead and scalp, with edema of the eyelids. A hair dressing containing bithionol produced a three-plus patch test reaction. Use of the same dressing at a later date initiated a prompt recurrence. A mother, aged 22, presented hands distended by a tight erythroedema. An intense zonal and weeping dermatitis occupied the dorsal surfaces. The next day, the inflammation had