Data derived from indirect calorimetry in patients with stable chronic pneumopathies were evaluated together with their pulmonary function data (spirometry, diffusing capacity, blood gases). Their basal metabolic rate was significantly higher (116.1% of the predicted value), this increase being more expressed in the patients with hypoxemia and with more severe obstructive disorder. In chronic obstructive pulmonary disease, the increased energy expenditure in hypoxemia was accompanied with increased lipid oxidation. There also was a correlation between the patients' nutritional status (evaluated by their body mass index) and their pulmonary function. These results confirm the impairment of pulmonary function in malnourished patients.