Sensitization to work-related and other common inhalation allergens was studied in 187 farmers by means of SPT and RAST. A positive RAST to house dust mites occurred in 6.4% and to storage mites in 5.3% of farmers. Sensitization to grain, pollen and animal dander was less frequent and a positive RAST to moulds was not found. There was a very strong association between a positive RAST to house dust mites and storage mites (odds ratio 173.6). Smoking seemed to be a risk factor for sensitization to mites, pollen, grain, and animal dander. Smokers who had lived in damp dwellings had a significantly increased risk of sensitization to mites (odds ratio 6.2-12.6), whereas this was not so with non-smokers (odds ratio 0.9-2.0).