Chl oral Hydrate (CH) is a sedative and hypnotic drug used in pediatric procedures owing to the low depressive effect it has on the respiratory and cardiac systems. Aim:To assess the efficacy of the drug in performing ABR and to systematize its use. Materials and Methods:A prospective cross-sectional study with 41 children without history of heart or lung disease. The initial dose of CH at 10% was 50mg/Kg, with a boost dose of 6mg/Kg administered 30 minutes later in cases in which there was no sedation. Drug effectiveness was established by sleep induction by 1 hour after the administration of the initial dose. Sleep occurrence was correlated with doses (50mg or 56mg/Kg), age, weight and gender.Results: All the 41 children who participated in the study took 50mg/kgof the agent and 23 of them slept within 30 minutes, 2 had respiratory complications, 16 had the 6mg/Kg boost dose and 13 fell asleep after 30 minutes. The 56 mg/kg dose presented a statistically significant effect on sleep induction (p<0.05) when compared to the 50mg/kg dose. Conclusion:CH produced a satisfactory effect with 50 mg/Kg dose plus 6mg/kg up to one hour after administration. Complications can occur regardless of the dose used. Braz J Otorhinolaryngol. 2010;76(4):433-6. BJORL ORIGINAL ARTICLE