Ten cases of pulmonary form of Lutz disease (South American blastomycosis) were studied in correlation of chest X-ray and spirometry. All of them showed the classic radiologic signs of nodular lesions, patchy infiltrations, fibrosis and emphysema. Four cases showed insufficiency of ventilatory function, probably derived from obstructive lesions; however, two other cases with X-ray signs of emphysema did not show spirometric abnormality. The authors emphasize the necessity of more investigation on lung function tests in a larger number of cases of pulmonary blastomycosis to establish definite conclusions in this unexplored field.