INTRODUCTION: Accurate placement of double-lumen endobronchial tube (DLT) is essential for optimal gas exchange and collapse of nondependent lung during one-lung anesthesia. The goal of this study was to determine if measurement of tracheal length from the preoperative chest X-ray can be used for the prediction of adequate length of left-sided DLT insertion. METHODS: 25 patients scheduled for elective thoracotomy under one-lung anesthesia were studied. After measurement of tracheal length from preoperative chest X-ray and of length from incisor to vocal cord during intubation, the patient was intubated with left-sided DLT to the depth of predetermined length from incisor to carina. The tube position was evaluated with fiberoptic bronchocsope. RESULTS: In 22 patients (88%) the DLTs were positioned satisfactorily, and in three patients it was required to reposition DLT. CONCLUSIONS: This technique may be useful for accurate placement of DLT for the one-lung anesthesia.