Wheezing and dyspnea appeared within an average of 4 months (range 1-24 months) after beginning the anti-TNF-α treatment. None of the patients presented with acute severe asthma. None of them had blood eosinophilia or rhinosinusitis during anti-TNF-α treatment. Patients 2 and 4 reported a past history of familial atopy. Patients 3 and 5 had a personal atopy with sensitization to airborne allergen. Lung function tests, performed after the onset of the respiratory symptoms, were normal in patients 1, 2, and 5 (with intermittent asthma). Only patient 2 was tested for bronchial hyperresponsiveness (BHR), and the test was positive with a provocative dose causing a 20% reduction in FEV1 in 1 s of 173 μg. Lung function tests revealed airway obstruction in patients 3 and 4 with persistent asthma (FEV1 80% predicted and 51% predicted, respectively). In patient 4, reversible criteria were not met (FEV1 increased from 2,960 mL to 3,140 mL, ie, by 8%). He had never smoked, had not been exposed to any significant air pollution, and had never previously suffered from dyspnea. Patient 3 had a reversible obstruction with prebronchodilator FEV1 of 2,660 mL and postbronchodilator FEV1 of 3,180 mL (19.5% increase). This patient reported having asthma when she was a child, but she had been asymptomatic for >5 years. This patient tested positive to dust and cat hair on a prick test, but she did not have a cat at home. Patient 5 had positive prick-test reactions to dust mites, cockroaches, and wormwood. Prick tests using anti-TNF-α were negative in four patients (patients 1, 2, 3, and 5). Total serum IgE levels, assayed before starting asthma treatment, were within the normal range in all patients (3-40 IU/mL). High-resolution CT scan of the lung was normal in all patients.