The relationship between immunological status and respiratory function was studied in 42 hemp workers and in 49 control workers. The highest prevalence of positive skin tests was recorded for a mixture of hemp and flax (64%), followed by flax (48%), hemp on a combining machine (41%), hemp on a carding machine (38%), hemp on spinning and weaving machines (33%), and hemp on a softening machine (20%). The prevalence of positive skin tests in control workers was smaller and varied from 21 to 5%. Increased IgE was found in 35.7% of the hemp workers and in 5.0% of the controls (P less than 0.05). Hemp workers with positive skin tests had a significantly higher prevalence of chronic respiratory symptoms than those with negative skin tests. Acute ventilatory capacity reductions did not differ in respect to the immunological status. An extract of hemp dust caused a constriction of an isolated guinea pig tracheal smooth muscle in vitro. Our data suggest that hemp dust as well as producing an immunological effect may exert an irritant effect on the respiratory system in exposed textile workers.