A functional evaluation was performed in 9 non-smoking patients suffering from sarcoidosis characterized, on chest roentgenograms, by hilar adenopathies (stage I). Frequency dependence of compliance (5 cases) and decreased conductance of the upstream segment (3 cases) were the major findings. From this it is concluded that, even at stage I, small-airway impairment may be documented in some patients, suggesting the existence of peribronchiolar granulomatous infiltration.