Background: The insertion of endotracheal tube is essential for most surgical operations, mechanically ventilated patient in ICU wards, During cardiopulmonary resuscitation and so for transport of patients. The aim of this study was determination of airway related distances in Iranian patients.

Methods: In a cross- sectional study during year 2007 in Imam Khomeini university Hospital a total of 75 ASA class I and II patients who were admitted to pulmonary ward evaluated for determination of incisor-vocal cord and incisor- carina distances. The nasal nare- vocal cord distance was determined too.

Results: A total of 71 patients, 45(63%) male and 26(36.6%) female were evaluated. The Incisor-vocal cord distance in males and females was 16.83±0.75mm against 15.04±1.12mm (P=0.03). The difference of nare-vocal cords and Incisor- vocal cord  distances was 2-3Cm

Conclusions: There was direct association between height and tracheal length in the study patients. The tracheal length (suitable insertion depth) in our patients was different from the recommendations (23 & 21 Cm for men and women) for non- Iranian, 25.9 versus 22.6 for Iranian men and women respectively. The difference of nasal nare-vocal cord and upper incisor-vocal cord distances in our patients was 2-3 cm, the lower range of accepted or reported one. We offer to do another experience with larger study group to apply the data to Iranian population.