Hilar displacement is one of the significant sign of pulmonary volume change. The hilar height ratio (HHR) is a value that express the normal position of a hilum in its hemithorax, and it is calculated by dividing the distance form the hilum to the lung apex by the distance from the hilum to the diaphragm. Displacement of one hilum is usually easy to detect but both are displaced in the same direction especially, recognition is more difficult. Knowledge of normal HHR allows evaluation of hilar positional change even when the relative hilar positions are not altered. Normal chest PA views of 275 cases taken at Korea University Hospital during the period of April 1978 to June 1979 were analized. The right hilum is positioned in lower half of the right hemithorax, while the left hilum is situated in the upper half of left hemithorax. The difference of hilar height ratio according to age group is slight, but there is significant difference between right-HHR and left-HHR. The valu of right-HHR is 1.28$pm$0.14, the value of left-HHR is 0.88$pm$0.09.