The frequency of contact urticaria provoked by certain fish prepared in the Danish fish industry was examined in 14 persons with atopia. In 71.4% of the test persons we found positive confirmation in a 20-minute scratch patch test to one or more fish species. All occluded patch tests were negative, while 33.9% of the scratch patch tests were positive. It was impossible to make a correlation between positive scratch patch tests and atopic allergen/total IgE. The investigation emphasizes that atopics have a higher frequency of contact urticaria to fish than have non-atopics.