Cardiac mensuration by the roentgenological heart volume method was carried out in healthy 302 cases of Koreanadults, 151 casses of male and 152 cases of female. Formulae used in this study are as follows. Predicted HeartVolume = K x Broad Diameter x Long Diameter X Greatest Horizontal Depth Relative Heart Volume = PredictedRoentigenological Heart Volume (total Vol.in ml) Body-Surface Area (meter squared) The constant K represents theproduct of an ellipsoid area factor and a correction factor for magnification of the cardiac image. Therefore, Kvalue used in this study is 0.42 for 200cm and 150cm of the focal-film distances in posterior-anterior and lateralviews respectively. The broad diameter is measured from the junction of the right atrum and the diaphragm to thejunction of the pulmonary artery and left atrial appendage. The long diameter is taken from the junction of thesuperior vena cava and right atrium to the cardiac apex. The greatest horizontal depth of the heart is measured onlateral view. Body-surface area is obtained by use of the Du Bois Nomogram. The results are as follows: 1.Predicted roentgenological heart volume in male is 641.53+9.22 ml and 565.97+7.00 ml in female, and shows increasewith age in the both sexes but no significant influence with body weight. 2. Relative heart volume in male is397.08+5.21 ml/m2 and 379.73+4.87 ml/m2 in female, and significant influence with age, height and weight isnegligible. 3. Roentgenological mensuration of the relative heart volume is considered to be simple and the bestmethod to express the standard of the heart size.