Conventional CT and HRCT can allow the differential diagnosis of cystic lung diseases to be limited or in many cases allow a confident specific diagnosis. Studies have shown that the distribution of the cysts, the thickness of the cyst wall and abnormalities of the lung parenchyma in between cysts can be used to arrive at a confident diagnosis of cystic lung diseases. Hence, in the appropriate clinical setting, this could obviate biopsy.Few cases of variable cystic lung diseases have been presented to show the role of CT in accurate localization and diagnosis with the appropriate clinical setting.Panacinar emphysema could be diagnosed on the basis of bilateral thin walled cystic lung changes predominantely involving upper lung zones with attenuated pulmonary vascularity. Cystic bronchiectasis showed segmental posterior basal cystic changes with few air fluid levels. Halo sign was diagnostic for aspergillosis in immunocompromised patients. Hepatic and lower lung lobe hydatid, could be accurately diagnosed. A large soft tissue mass encasing the bronchus implicating the whole lower lung lobe was diagnosed as bronchogenic carcinoma proved by biopsy. Elevated diaphragmatic cupola with pleural based encysted collections and almost free both lung fields was the CT criterion for diagnosing encysted empyema. Active TB was well shown as bronchopneumonic pulmonary infiltrate with thick walled cavities associated with consolidation collapse of the other lung. With history of haemoptysis, apical cystic lung lesions on CT scan preserving the anterior segment of the upper lobe were diagnosed as bronchiectasis sicca haemorrhagica.