Introduction: An anthropometric distance is crucial for an easy endotracheal intubation and correct placement of endotracheal tube in the trachea. There may be a racial difference of the anthropometric measurement. So we measured the anthropometric distances of the upper airway in Korean adult patients. METHODS: A standard anesthetic induction and maintenance was performed in 100 adult patients following endotracheal intubation. Various anthropometric measurements were determined while the patients head were in a neutral position. Thyromental and sternomental distance were measured. A distance from upper central incisor to carina or cricoid cartilage was directly measured using fiberoptic laryngoscope. However, the length from upper central incisor to midtrachea & the cricoid cartilage-carina distance were indirectly calculated from the above measured distances. Correlation analyses were also performed between age, height, or weight and the above measured anthropometric distances. RESULTS: The mean distances from upper central incisor to carina, cricoid cartilage or midtrachea were 25.5+/-1.8, 13.9+/-1.9, or 19.8+/-1.8cm respectively. The mean distance from cricoid cartilage to carina was 11.6+/-1.4cm. Thyromental and thyrosternal distance were 6.6+/-0.9 and 15.7+/-1.5cm respectively. All mean anthropometric distances of male were longer than those of female patients. Thirty-eight patients (38%) had the thyromental distance < or = 6cm while one patient (1%) had thyrosternal distance < or = 12.5cm. A good correlation (r< or =0.6) was observed between height and upper central incisor-carina distance. CONCLUSIONS: This study suggests that these measured anthropometric data are useful for an easy endotracheal intubation and accurate endotracheal placement in the trachea.