The auther has studied the measurement of the length of the base of the nose to the carina, the upper incisor to the carina, trachea, left and right main bronchi, the number of cartilage and angle of the main bronchi in 14 cases of autopsy (3 males, 11 females) in Korean infants which were divided into 3 total body length groups and discussed metrically according to each different groups. The result are as follows ; 1) According to the length of the base of the nose to the carina, the upper incisor to the carina, trachea, left and right main bronchi : a group with total body length below 50 cm was 10.45 cm, 9.21 cm, 2.88 cm, 11.9 mm, 5.6 mm : in group of body length measuring 50~70 cm, there was 11.7 cm, 10.65 cm, 3.22 cm, 17.47 mm, 7.58 mm : another group above 70 cm was 14.6 cm, 13.4 cm, 4.22 cm, 24.2 mm, 11.2 mm. 2) According to the antero-posterior diameter of the trachea, left and right main bronchi : a group showing below 50 cm of the total body length was 4.4 mm, 3.4 mm, 4.2 mm : in group of 50~70 cm body length, there was 5.6 mm, 3.5 mm, 4.32 mm : in another group above 70 cm, there was 6.12 mm, 4.7 mm, 5.67 mm. According to the transverse diameter of the trachea, left and right main bronchi : a group below 50 cm of total body length showed 5.4 mm, 3.8 mm, 4.4 mm : in another group of 50~70 cm body length, there was 6.30 mm, 4.20 mm, 4.81 mm : in another group above 70 cm, there was 7.3 mm, 5.3 mm, 6.05 mm. 3) The angle of left and right main bronchi from the midline is 40~60 degree (mean : 51.5 degree) on the left side and 20~44 degree (mean : 31.1 degree) on the right side. 4) The number of the cartilage of the trachea in all groups, was 14~19 (mean : 16) : the left and right main bronchi had 7 and 3 in numbers. 5) The increment of the average length and diameter of the trachea and main bronchi shows a tendency toward linear relationship, varying with development of the total body length rather than age, and no significant sex difference was found.