Atopic sensitization was studied using skin tests on 93 randomly selected, non-smoking dairy farmers. The farmers lived in the municipality of Pielavesi, in eastern Finland. The reference group consisted of 84 non-smoking teachers randomly selected from all the teachers employed by the city of Kuopio, which is in the same administrative district as Pielavesi. Thirty-four allergens were included in the test panel. For testing these allergens, we used the prick technique with disposable precision lancets. The prevalence of a positive skin-test reaction (weal size at least 3 mm X 3 mm) was 19.4% among the farmers and 15.5% among the teachers. The number of positive reactions to cow epithelium was significantly greater among farmers than among teachers. Only to mugwort pollen did teachers have significantly more positive reactions than farmers. Teachers had stronger reactions than farmers to cat, dog, and horse epithelium. Farmers had significantly stronger reactions than teachers to cow epithelium and oat pollen. Our results emphasize the importance of cow epithelium and oat pollen as occupational sources of allergens among dairy farmers.