STUDY OBJECTIVE Transtracheal ultrasound has been described as a method to evaluate endotracheal tube placement. Correlation between sonologist experience and the successful use of transtracheal ultrasound to identify endotracheal tube location has not been examined. Our objectives were to evaluate emergency physicians' ability to correctly identify endotracheal tube location using transtracheal ultrasound and to evaluate the role operator experience plays in successful identification of tube placement. METHODS This was a cross-sectional, single-blinded study conducted in a cadaver laboratory. Two cadavers were used as models. One cadaver had an endotracheal tube placed in the esophagus, and the second had the tube placed in the trachea. Participants were asked to evaluate tube placement using transtracheal ultrasound and to record their interpretation. Examination clips were reviewed by the emergency ultrasound fellowship director. Descriptive statistics and χ(2) test were used for analysis. RESULTS Twenty-nine participants were included, 8 (27.6%) of whom were considered to be "most experienced" based on previous ultrasound experience (>150 scans). Eleven of 29 correctly identified esophageal intubation and 18 of 29 correctly identified tracheal intubation, resulting in a sensitivity of 62.0% (95% confidence interval [CI], 42.3-79.3) and a specificity of 37.9% (95% CI, 20.7-57.7). Transtracheal ultrasound performed by the most experienced sonologists showed better sensitivity and specificity, 75.0% (95% CI, 34.9-96.8) and 62.5% (95% CI, 24.5-91.5), respectively. CONCLUSION Most participants obtained adequate images, but correct interpretation of the images was poor. The most experienced sonologists correctly identified tube location more often. Additional education would be required before adopting this method.