SUMMARY.— A wave of contact dermatitis due to an optical whitener in washing powders is occurring in Copenhagen. A report is given on 30 patients diagnosed in only 2 months. The clinical features are those of a textile dermatitis. The typical lesions are irregular, faintly red or red‐brown spots with a finely wrinkled or crackled surface; by confluence a reticulate pattern is formed. In many cases the changes are minimal and may easily be overlooked, but there is nearly always rather severe itching. Copyright © 1969, Wiley Blackwell. All rights reserved