Sixty-seven workers in the detergent industry whose exposure to proteolytic enzyme ceased in 1969 have been examined clinically and functionally. By comparison with 42 lightly and moderately exposed subjects, 13 heavily exposed subjects showed significant loss of pulmonary elastic recoil as evidenced by increased lung volumes and increased pulmonary compliance, but there were no differences in airways resistance or other parameters of lung function. No difference was found between the two groups in relation to symptoms on exposure, current exercise tolerance, skin reactivity to the proteolytic enzyme alcalase, trypsin inhibitor capacity, and other features. An increased clinical grade of breathlessness was associated with evidence of airways obstruction, but not of altered elastic recoil. Comparison of the data on lung mechanics with results obtained in 1970 suggests that partial recovery of pulmonary elastic recoil may have occurred in some cases. It is also suggested that diminished elastic recoil, in the absence of impairment of transfer factor at rest, may reflect altered physical properties of the lung fibre network without loss of effective surface area available for gas exchange.