Structure, size of trachea and bronchial tree are well known in modern time. There are hundreds of research about respiratory anatomy havebeen done in developed countries. Our team interested that when and how airway structure to become investigated. In Shinong king’s period (2838 – 2699 BCE) human anatomical feature was described rough and ready and note down in books and other treatises. In Guang – Tae king’s period ( 2698 BCE), the trachea divided into 7 pieces in the thorax cavity described in medical treatise named “Nei King” .Since 8th century BCE when autopsy introduced in India, the morphology started in science as evidence based science. All the theories at the time based on research findings represent that medical science has been developed as a evidence based science since 16thcentury in Mongolia. The late 18 century, period of renaissance technology and science, structures of the respiratory system start investigated in detail. 1889 V.Ewart , There are many scientists attempt to measure size of airway structures, unfortunately the results were quite different that may due to material, method and anatomical feature differences. Thus, future intensive research is needed in order to prosecute out previous docotr’s and scientists studies.

Background:In recent years the respiratory tract diseases, including chronic bronchitis and others, are increasing, and all developed countrieshave already determined the normal Airway measurements. But there is a lack of the studies on normal tracheal and bronchial branches measurements, which could be serve as the control groups for the pathological ones. Thus the purpose of this study is to measure and identify tracheal tube and I-III bronchi of health Mongolian adults. Materials and Methods:The materials were developed by bronchography procedure, and histological methods; and the results assessed by hypothesis testing. Results: The trachea lenght for male was 120.54±4.07 mm; thebronchi length: right 1stbronchi as 28.00±3.04мм, the left - 42.79±2.18 mm, the 2ndbronchus - 25.99±1.38 mm, the 3th bronchus - 24.95±1.80 mm. The tracheal diameter for female was 17.95±2.27 mm; the bronchial diameter: 1stbronchus /right/ - 12.86±0.80 mm, the left - 11.44±0.60мм, the 2ndbronchus - 9.28±0.40 mm, the 3rdbronchus - 4.69±0.35 mm. Conclusion:The results show that the trachea and I-III bronchi length and diameter measurements’ differences are not statistically significant on gender, p=0.879 and p=0.669 separately.