Bronchogenic cyst, pulmonary sequestration, congenital cystic adenomatoid malformation and congenital lobar emphysema are four major congenital cystic pulmonary diseases that represent a spectrum of closely related anomalies arising at early stage of embryonic lung bud maturation. Most of them present with recurrent pulmonary infections or chest pain since childhood and usually the diagnosis is made at this age. Sometimes the lesions are silent and found at adult age. We retrospectively analyzed the plain chest radiograms for 30 patients with a lung bud anomaly. The diagnosis was established by surgery and biopsy, but bronchography, computed tomography and ultrasonography aided in the diagnosis, seventeen bronchogenic cysts, 8 pulmonary sequestrations, 2 congenital cystic adenomatoid malformations, 2 congenital lobar emphysema and 1 congenital bronchial stenosis are included in this study. Nine out of 13 intrapulmonary bronchogenic cysts involvoed the lower lobes : thin-walled cysts with or without air-fluid level were the characteristic chest roentgenographic finding. However, mediastinal bronchogenic cyst showed well-marginated mass. The pulmonary sequestration showed similar cystic mass with or without air-fluid levels in five out of eight patients, but the cyst wall was not so sharply defined as in the bronchogenic cyst. In two patients of congenital cystic adenomatoid malformation, a large thin-walled cyst with air-fluid level was noted and differentiation form intrapulmonary bronchogenic cyst was difficult both by chest roentgenogram and computed tomography. Two partients of congenital lobar emphysema and one patient of bronchial stenosis showed unilateral hyperlucent lung without discrete cystic mass formation.