The esophageal obturator airway (EOA) has been approved for use in cardiopulmonary resuscitation (CPR) since 1973. Complications reported with its use include esophageal rupture, aspiration, and inadvertent tracheal occlusion or intubation with the obturator. Five cases of unrecognized tracheal intubation occurring in 170 cases of EOA use during CPR are reported. Records were analyzed for extent and treatment of injuries in the field and the hospital, blood gas levels before and after replacement of the erroneously placed EOA with an endotracheal tube (ETT), and outcome. Blood gas analysis confirmed absent ventilation and profound acidosis following tracheal intubation with the EOA with average EOA arterial blood gases: pH 6.9/pCO278/pO247. Mortality from this complication was 100%. Tracheal intubation with the EOA is under-recognized and under-reported. It is a potentially lethal complication. The EOA should be replaced with standard bag mask technique or preferably endotracheal intubation in the field by emergency medical technicians.