We report 3 patients (26, 31, and 33 years) who worked at the same fish farm for several years. They experienced symptoms of rhinoconjunctivitis and bronchial asthma while classifying fish by size. Their asthma gradually worsened to the extent that it became persistent and required daily medication with inhaled corticosteroids and bronchodilators. Symptoms improved during weekends and holidays. All 3 patients could eat turbot. Our study showed that the patients were allergic and that sensitization was probably by inhalation. The allergens were parvalbumin in 1 case and a different allergen in the remaining 2 patients.