Clinical experience during one-lung anesthesia using a new right-sided endobronchial tube (Portex Ltd, Hythe, Kent, UK) is reported in 148 patients with cancer of the left lung. The method allowed a reliable airtight separation of the lungs as well as right upper lobe ventilation in all cases. The new tube also allowed proper upper lobe ventilation in cases with anatomical variations of the length of the right main bronchus. The intubation technique was greatly simplified when compared with commercially available double-lumen tubes. Airway pressures and arterial blood gases were similar to those obtained with standard double-lumen tubes during one-lung ventilation. There were no complications due to the new tube system.