Objective: To determine the accuracy of a syringe esophageal detector device (EDD) for detecting esophageal intubations in an out‐of‐hospital setting.Methods: Prospective, observational study of adult (age ≥18 years) patients intubated by paramedics from October 1993 through May 1994 in an urban emergency medical services (EMS) system. Paramedics were instructed to record the EDD reading after endotracheal tube placement. However, paramedics were instructed not to modify their tube locations based on the EDD reading. Tube placement was evaluated by a physician upon patient arrival at a local ED.Results: Paramedics performed 374 intubations during the study period, and in 213, the EDD was used. Of these 213 patients, 45 were excluded from analysis (32—tube placement not confirmed, 11—paramedic uncertain of EDD reading, 2—too young). In the remaining 168 intubations, the EDD correctly identified 5 of 10 esophageal intubations (sensitivity 50%; 95% CI: 19%, 81%). The EDD correctly identified 156 of 158 tracheal intubations (specificity 99%; 95% CI: 96%, 100%).Conclusions: In this paramedic field study, the EDD demonstrated poor sensitivity for esophageal intubations. Further EMS studies of the EDD are needed to clarify the value of the device in out‐of‐hospital emergent clinical intubations.