: This morphometric study of main bronchus was performed to provide the basic data necessary for anatomists, anesthetists and emergency medical technicians. A total of 48 cadavers, 33 men and 15 women, were used in this study. When it comes to their average age, men were 70 years old (50 to 91 years old), and women were 74 years old (47 to 92 years old). For this study, the length of the left and right main bronchi and the angle between them, and the first bronchial cartilage's each anteroposterior diameter, transverse diameter, vertical height, and distance between posterior ends of cartilage were measured.As for the length, left length was longer than right length regardless of gender, and there was no significant difference between men and women. When it comes to anterorposterior diameter, transverse diameter, and distance between posterior ends of the first bronchial cartilage in main bronchi, the right side was longer and wider than left side regardless of gender, but statistical significance was shown only in the distance between posterior ends of cartilage. Vertical height of the first bronchial cartilage in main bronchi did not show any difference between the left and right and between men and women, and men cadavers had a very large individual difference from 2.35 mm to 9.22 mm. As for the angle of the main bronchi's separation from trachea's major axis, the left side was larger than the right side in both men and women cadavers and it was larger in men than women, but there was no significant statistical difference. Lastly, as for the length of the main bronchi, the right and left lengths in men were 16.83±1.36 and 37.26±1.42 mm respectively; and the right and left lengths in women were 16.90±2.26 and 36.08±3.39 mm respectively. These results are expected to be used as the basic clinical data useful for medical procedures of emergency care practitioners, anesthetists and emergency medical technicians.