Chronic eosinophilic pneumonia is a rare interstitial lung disorder, which causes diagnostic difficulties. Often the disease is diagnosed correctly after several weeks or months following initial presentation. The aim of the study was to prospectively evaluate peculiarities of manifestation of idiopathic chronic eosinophilic pneumonia (ICEP), which may allow to improving early diagnosis. Twenty patients with ICEP were involved in this investigation. The cases of acute eosinophilic pneumonia and cases of chronic eosinophilic pneumonia of known origin were excluded. To define archetypal signs of the idiopathic chronic eosinophilic pneumonia, 3 comparable groups were selected. They were the group of 50 patients with community-acquired pneumonia (COP); the group of 21 asthmatic patients with COP, and the cluster of 10 patients with morphologically confirmed cryptogenic organizing pneumonia (OP). Clinical and radiological manifestation of ICEP was similar to COP and cryptogenic OP manifestation. We have found that chest pain; fine rales and pleurisy were unrepresentative for ICEP. However, blood eosinophilia was typical sign of ICEP and wheezing was a frequent observation. Usually ICEP patients had relative mild clinical symptoms and moderate increased C reactive protein (CRP) level even in cases of multiple pulmonary infiltrates. In conclusion, in cases of not typical pneumonia course, i.e. non-resolving or recurrent pulmonary infiltrates; relative mild clinical symptoms and moderate increased CRP level with multiple pulmonary infiltrates; blood eosinophilia and/or signs of airway obstruction eosinophilic pneumonia should be suspected and bronchoalveolar lavage and/or bronchoscopic lung biopsy performed.