To evaluate potential predictors of atopy, 3353 workers from various occupations were classified according to airborne exposures into three groups: (1) 1213 control workers with no measurable exposures, (2) 815 workers with gas and fume exposure, and (3) 1325 workers with organic dust exposure. Atopic status was determined by prick skin testing with common allergens. Workers exposed to organic dusts had a lower prevalence of skin test reactivity than either controls or gas- and fume-exposed workers. Skin test reactivity also decreased with age and was higher in nonwhite workers compared to white workers. No difference in skin test reactivity was seen between female and male workers, nor between smoking and nonsmoking workers. A logistic regression analysis that controlled for the correlation between the predictive factors confirmed the results of the crude analyses. It is suggested that atopic workers exposed to organic dusts might selectively leave the industry.