An N2 wash-out technique was used to estimate the small airways function in 22 male workers, exposed to the asthma-inducing amine piperazine, and in 22 referent subjects, with similar smoking habits and age. The volume of trapped gas (VTG) was determined before and after a bronchial provocation with an aerosol of 0.25 ml 0.01% metacholine solution. No difference in VTG was observed between the piperazine-exposed workers and the referent subjects, either before or after the metacholine provocation. This indicates that a time-weighted average (TWA) exposure of about 0.1 mg piperazine/m3 does not cause small airways disease in non-asthmatic workers. Further, age and smoking habits were significantly associated with VTG.