A clinical survey of workers exposed to laboratory animals in a pharmaceutical company was designed to discover the prevalence and severity of symptoms of laboratory animal allergy (LAA). The overall prevalence of the condition was 30%, and two distinguishable LAA syndromes, termed regional and progressive LAA, were found. The first is characterised by rhinitis with negative skin prick tests. The second consists of rhinitis leading progressively to asthma with positive prick tests. Prick tests were useful diagnostically only in the latter. Atopes were shown not to be at special risk of developing LAA, but if they did so were more likely to progress to asthma. The implications for selection and management policy are outlined and specific measures for the further study of LAA are proposed.