In spite of recent introduction of such highly sophisticated diagnositc modalities as computerized tomography, cardioangiography and polytomography the simple PA chest remains as an essential and important method of chest diagnosis especially in terms of vascular diseases of the lung and heart. Until, recently, however, the interpretation of chest X-ray has been largely dependent on much subjective observation of roentgen anatomy of the chest. Several years ago Simon proposed a quantitiative approach to interpretation of the chest in an attempt to make the judgement more objective. In the present study we have carried out a clinical study on normalities of the standard PA chest of Korean adults. The materials consisted of 216 normal chest films. Age ranged form 20 to 60 years and sex distribution 103 males and 113 females. We counted the number of vessels in both lung fields, measured the diameter of the basal artery and investigated the level of hilum points as well as hilar istance. There were 9 to 11 vessels in the upper zone and 9 to 12 in the lower zone. There sere no significant sex difference. The number of vessels was not affected by aging. The average diameter of the basal artery was 11.7$pm$2.4 mm in the right lower zone and 12.2$pm$2.9mm in the left lower zone in male and 10.9$pm$2.2mm in the right lower zone and 10$pm$1.8 mm in the left lower zone in female. There was significant sex difference ( P 0.01) . Aging seemed no to be affected the size of the basal artery. The majority of hilum point was located at the level of 5-6th rib at axillary portion and the left hilar point is 0.3-2.0cm higher in location than the right. The hilar distance was 4.1$pm$0.4cm on the right 5.0$pm$1.1cm on the left in male and 4.0$pm$0.7cm on the right and 4.7$pm$0.5cm on the left in female. There was significant sex difference( p 0.01). There was signigicant difference in size of the basal arteries and hilar distance between the Koreans and Englishman but the numbers of vessels ere not significantly different.