The Supreme laryngeal mask airway (LMA) is a new single-use polyvinyl chloride supraglottic device that combines the functionality of the ProSeal and Fastrach airways. High oropharyngeal leak pressures are important as they indicate airway protection, feasibility of positive pressure ventilation and likelihood of successful LMA placement. The oropharyngeal leak pressure of the LMA Supreme is not well established versus the LMA ProSeal. This study was designed to compare the safety and efficacy of the LMA Supreme versus the LMA ProSeal in elective ambulatory procedures.