Objective To investigate the Churg-Strauss syndrome (CSS) associated lung involvement,concentrating on clinical characteristics,pathological findings of lung involvements,response to treatment,and prognosis.Methods We retrospectively analyzed the characters of the clinical manifestations,thin-section CT and pathological findings of CSS.The study involved 16 patients.Clinical data were obtained by chart review.All patients underwent transbronchial lung biopsy (TBLB).Six of them underwent surgical lung biopsy as well.Results The patients included 7 men and 9 women,aged from 14 to 61 years (median,47.5 years).Extrathoracic organs involved included nervous system (7/16) and skin (5/16).Respiratory symptoms included cough (12/16),exertional dyspnea (11/16),hemoptysis (4/16),and chest pain (3/16).CT findings included bilateral ground-glass opacities (12/16),bilateral patchy opacities (12/16),and centrilobular nodules (6/16).The pathological findings of TBLB demonstrated increased eosinophils (3/16),vasculitis (3/16),and interstitial pneumonia (16/16).The pathological findings of surgical lung biopsy of 6 cases showed ne-crotizing vasculitis in 4 cases,capillaries in S,eosinophilic pneumonia in 3,granulomas in 2,and airway abnormalities in 3.All patients improved in symptoms after therapy during the study period (range,3 to 51 months; median,15 months).Conclusions Asthma may be present in CSS patient when there is bronchial involvement.Ground-glass opacities and consolidation seen on high-resolution CT reflect the presence of eosinophilic pneumonia,vasculitis,and pulmonary alveolar hemorrhage.TBLB has significant limitations for the diagnosis of CSS.Early diagnosis and therapy can result in satisfactory prognosis.