Video-assisted thoracic surgery (VATS) has been increasingly used because of it is a less invasive procedure than the open thoracotomy. Neither commercially available double-lumen tubes nor the univent tube can be used in small children. An ordinary uncuffed tracheal tube was introduced into the main bronchus of the right lung. This technique proved to be a simple and effective method of isolating and ventilating the other lung. We describe our experience providing one-lung ventilation with ordinary endotracheal tube during VATS in two young children. (Korean J Anesthesiol 2001; 40: 824 ~ 828)