BACKGROUND AND OBJECTIVES: To verify the prevalence of correct position of the tracheal tube after children intubation in two reference intensive care unit in south of Brazil. Evaluate the accuracy of the different methods and suggested formulas to estimate the depth insertion of the endotracheal tube. METHODS: A cross-sectional, observational study was designed. It was included all children intubated at pediatric ICU in Hospital São Lucas da PUCRS and Hospital de Clínicas de Porto Alegre between August and September of 2004. Patient with vertebral deviations, after surgeries or with airway malformations was excluded. In the first 24 hours after intubation the patients’ charts were reviewed, a questionnaire was filled, the physician who was responsible for the procedure was interviewed and the chest radiogram was analyzed. The position was considered correct if the tube extremity was between the first thoracic vertebra (T1 ) and the third thoracic vertebra (T3 ) with a tolerance of 0.5 cm. The different formulas to estimate the depth insertions of the endotracheal tube were applied in all patients and this distance was measured with the aim of evaluate the accuracy of each method. RESULTS: The endotracheal tube position was correct in 60% (21 / 35) of the intubated children. A half of the physicians used some formula to estimate the depth of tracheal tube insertion. There was no difference between the group that used any formula and the group that didn’t use in predict the correct tube position (75% versus 47% p = 0,2). The most accurate method to estimate the endotracheal tube location was age group (68%; p = 0.02) when compared with height, tube diameter and age. CONCLUSIONS: The methods that are used to estimate the length of endotracheal tube to be introduced in children have low accuracy. It is imperative to develop a sharper and practical way to determine this distance