Ιnterleukin-6 (IL-6) has been identified as an early biochemical marker of inflammation both in animal and human studies. With this study, we sought to examine the development of local inflammation of the glottic tissues in correlation with the duration of intubation in anesthetized pediatric patients. We measured IL-6 levels in the organic material isolated from the tip of the tube post-extubation in 48 children aged 7 months to 14 years old who were submitted to a total of 72 surgical procedures. A statistically significant positive correlation (ρ = 0.28, p = 0.05) was detected among duration of anesthesia and IL-6 concentration. The odds of having detectable IL-6 levels rose by 36.7 % for every 10 min of anesthetic duration (p = 0.045). In conclusion, the increase of IL-6 in relation to the duration of the intubation indicates an increased risk of inflammation.