A 43-year-old woman presented with an 8-month history of progressively worsening nonproductive cough. She had been treated with antibiotic agents for presumed bronchitis, but her cough continued to worsen. Her vital signs were normal, the pulmonary examination was notable for wheezing in both lungs, and the white-cell count, including the absolute number of eosinophils, was normal. Results of pulmonary-function tests suggested an obstructive defect that did not respond to bronchodilators. Bronchoscopy revealed diffuse nodules in the tracheobronchial mucosa (Panel A). Biopsy of a nodule revealed eosinophilic infiltration of the bronchial mucosa. There was no evidence of tumor, infection, vasculitis, or granulomas. The patient received a diagnosis of eosinophilic bronchitis. Patients with eosinophilic bronchitis usually have normal results on spirometry, but diffuse nodules in the tracheobronchial mucosa cause obstruction that does not respond to bronchodilators. The patient was treated with systemic glucocorticoids and inhaled budesonide for 1 month. At 1 month after the start of therapy, follow-up bronchoscopy revealed a considerable decrease in the size of the nodules in the tracheobronchial mucosa (Panel B), repeat pulmonary-function tests revealed resolution of the obstructive defect, and the patient’s clinical symptoms had resolved completely. Because small nodules were still visible, the patient received inhaled budesonide for 2 additional months, after which the mucosal nodules in the trachea were no longer present. At follow-up 6 months after the start of therapy, the clinical symptoms had not recurred.