The respiratory health of 230 female and 1,734 male farming students (FS) and 407 male rural controls was analyzed. A significantly increased prevalence of cough (6.9%) was reported among the male FS compared to the controls (2.5%). Measured FEV1 and FVC did not differ between the male FS and the controls, as opposed to significantly higher values among the female FS compared to a random sample of urban females stratified for height. Skin prick test (SPT) to house dust and storage mites was significantly more prevalent among the controls (18.7%) compared to the male FS (12.8%) and the female FS (11.9%). The size of the house dust mite weal and the number of positive skin prick reactions were significantly associated with bronchial hyperreactivity. The difference in lung function among the female FS and the lower prevalence of skin reaction among the male FS and female FS probably reflects a healthy workers selection.