Lung agenesis is a rare congenital anomaly. It can be found single or double sided. While, double sided agenesis couldn't been survive, in single cases survive until adult or more advence of living is possible. This anomaly is generally diagnosed in childhood. However, incase if, unilateral pulmonary agenesis doesn't accompany with any other the serious anomaly, the asymptomatic cases are detected incidentally in advanced age. Cases associated with other system anomalies have a ratio with 60%. In our study 17-year-old female patient who had left pulmonary agenesis found by computed tomography. Since of its clinical importance this anomaly presented with the related literature.