OBJECTIVE To determine the accuracy of the esophageal detector device (EDD) in predicting correct endotracheal tube (ETT) placement in a newborn-piglet model. METHODS We used an EDD, comprising a 5-, 10- or 20-mL syringe attached to 4-mm tubing fitted to a 15-mm ETT adapter, to aspirate gas from cuffed or uncuffed ETTs placed in the trachea or esophagus of each newborn piglet. During aspiration, we noted any resistance encountered while pulling back the plunger of the syringe and recorded the total volume of gas aspirated into the syringe. A positive test, signifying tracheal ETT placement, was defined as the ability to freely aspirate gas without resistance and the aspiration of enough gas to fill the entire volume of the syringe. A negative test, signifying esophageal ETT placement, was defined as resistance encountered during the aspiration of gas into the syringe and rebound of the syringe plunger, leading to aspiration of a volume of gas less than the total volume of the syringe. RESULTS We conducted 444 trials (222 for uncuffed ETTs, 222 for cuffed ETTs). ETT size ranged from 3.0 to 4.5 mm. For cuffed ETTs, the 5-mL syringe had a sensitivity of 100% and a specificity of 5%, the 10-mL syringe had a sensitivity of 95% and a specificity of 16%, and the 20-mL syringe had a sensitivity of 86% and a specificity of 97%. For uncuffed ETTs, the 5-mL syringe had a sensitivity of 100% and a specificity of 5%, the 10-mL syringe had a sensitivity of 97% and a specificity of 24%, and the 20-mL syringe had a sensitivity of 81% and a specificity of 100%. CONCLUSIONS No syringe had 100% sensitivity and specificity in correctly predicting ETT placement. The 20-mL syringe had the highest combination of sensitivity and specificity. Further studies are warranted to determine whether the EDD using a 20-mL syringe would aid in the prediction of correct ETT placement in the pediatric population.