In the unusual manifestation of right upper lobe collapse confusing with mediastinal or parenchymal mass, both alteration of the pulmonary vessels and shifting pattern of the collapsed lobe to the periphery on supine position are the key to the diagnosis of it rather than mediastinal or parenchymal mass. The mechanisms of these unusual manifestations are obscure, however lobar torsion and gravity factor are considered to be a main process. Authors have experienced 2 cases of unusual manifestations of right upper lobe collapse due to bronchogenic carcinoma during resent 2 years in Kyung Hee University Hospital, and present radiologic findings.