Medical examinations were performed in a group of 76 Polish farmers heavily exposed to grain dust during harvesting and threshing, and in a group of 63 healthy urban dwellers not exposed to organic dusts (controls). The examinations included: interview concerning the occurrence of respiratory disorders and work-related symptoms, physical examination, lung function tests, and allergological tests comprising skin prick test with 4 microbial antigens associated with grain dust and agar-gel precipitation test with 12 microbial antigens. As many as 34 farmers (44.7%) reported the occurrence of work-related symptoms during harvesting and threshing. The most common was dry cough reported by 20 individuals (26.3%). Dyspnoea was reported by 15 farmers (19.7%), tiredness by 12 (15.7%), chest tightness by 8 (10.5%), plugging of nose and hoarseness by 5 each (6. 5%). No control subjects reported these work-related symptoms. The mean spirometric values in the examined group of farmers were within the normal range, but a significant post-shift decrease of these values was observed after work with grain. The farmers showed a frequency of the positive early skin reactions to environmental allergens in the range of 10.8 - 45.5%, and a frequency of positive precipitin reactions in range of 3.9 - 40.8%. The control group responded to the majority of allergens with a significantly lower frequency of positive results compared to the farmers. The obtained results showed a high response of grain farmers to inhalant microbial allergens and indicate a potential risk of occupational respiratory diseases (such as allergic alveolitis, asthma, Organic Dust Toxic Syndrome) among this population