Objective To investigate the effects of chin lift on the patency of upper airway in normal conscious adults using magnetic resonance imaging (MRI).Methods Sixteen healthy volunteers aged 21-35 yr with a body mass index of 17-26 kg/m2 were enrolled in this study.The subjects lay on their back with their heads slightly extended.The lower jaw was first left in standard position.The mouth was slightly open (the distance between the upper and lower incisors was 0.5 cm).The chin was then lifted upward.The upper airway (from the base of slull to the level of vocal cord) was scaned by MRI along the median sagital plane.The length of soft palate,root of tongue and epiglottis and the area of pharyngeal cavity were measured.The position of the rim of epiglottis was examined.The mean percentage changes induced by chin lift were calculated.Results Compared with standard position,chin lift significantly prolonged the length of soft palate,root of tongue and epiglottis and increased the area of pharyngeal cavity.The percentage change in the position of the rim of epiglottis was largest after chin lift.Conclusion Chin lift significantly improve the patency of the upper airway in conscious adult by changing the position of the rim of epiglottis and increasing the area of pharyngeal cavity.