In non-smokers the underlying causes for chronic persistent cough (CPC) e.g. chronic cough without diagnostic chest X-ray or pulmonary function test--are usually as follows: several common upper airways diseases, bronchial (cough type) asthma, gastrooesophageal reflux or treatment with an ACE (angiotensin converting enzyme)--inhibitor. In 10% of CPC however the cause remains uncertain. We report a 30 year old non-smoker with severe coughing and repeated vomiting for two months. No laboratory or technical data could be collected suggestive of a common cause of CPC: Upper airways disease, bronchial flow limitation or hyperresponsiveness, ACE inhibitor medication, B. pertussis infection, gastrooesophageal reflux disease (by 24 hours pH-probe) were ruled out. Fiberbronchoscopic findings remained unremarkable, except for the bronchial biopsy specimen, which showed moderate eosinophilic inflammation of the mucosa and marked thickening of the subepithelial layer. Since the cough was non-productive, sputum induction with 3 ml nebulised 3% NaCl solution was performed. 28% of the granulocytes were eosinophil stained. A low quality morning sputum (< 1 ml) showed 21% eosinophilia. Thus, the diagnosis of eosinophilic bronchitis was established. 400 micrograms budesonide dry powder inhalations b.i.d. for one week resolved the cough, treatment was stopped after three weeks. No recurrence was seen two months later. Both the cough type asthma and the eosinophilic bronchitis could represent a form fruste of classical bronchial asthma beyond wheezing or dyspnoea, but with the common main symptom: cough. Since hyperresponsiveness and cough are phenotypic hallmarks of cough variant asthma, in eosinophilic bronchitis--beside cough--another two features of asthma are present: eosinophilic inflammation of the mucosa along with sputum eosinophilia and subepithelial layer thickening. Not surprisingly, eosinophilic bronchial inflammation could be shown in patients with cough variant asthma as well, who--up to 56% during a four year-period--develop classic asthma. The long-term outcome of eosinophilic bronchitis is not known, however. Thus, asthma, cough variant asthma and cough due to eosinophilic bronchitis can mirror different phenotypes or phases of the same entity. CPC due to either the cough type asthma or the eosinophilic bronchitis is like asthma fast responding to inhalative steroids. (Induced) sputum staining should be added to the diagnostic armamentarium of CPC.