Authors recently experienced a case of traumatic pulmonary pseudocyst in 4 year-old girl. Traumatic pulmonary cyst is a rare complication of blunt thoracic trauma, simulating surgical conditions such as lung abscess, localized empyema, or congenital bronchogenic cyst. Unless infection is supervened, surgery is not indicated because of its spontaneous regression. In this article, authors present the case and review the traumatic pulmonary pseudocyst with related articles.