The use of automated salmon processing equipment in a factory has been shown to cause occupational asthma in the workforce by the generation of respirable aerosol contaminated with salmon protein. The affected individuals develop asthmatic symptoms and signs three weeks to three months after exposure. The diagnosis is made by clinical history, pulmonary function tests and the detection of specific serological markers. Affected individuals should be removed from exposure to aerosol to prevent the development of chronic asthma. A cross sectional survey demonstrated a prevalence rate of 8% in the exposed workforce. A nested case control study described the attributes of the cases. The chances of becoming a case were greatly increased by being a smoker [OR = 10.9] and less by being atopic [OR = 1.9]. Environmental hygiene measures to reduce aerosol from the gutting machines will reduce the problem but continued health surveillance of an exposed workforce is recommended to detect clinical and serological markers of disease.