Lung-isolation techniques are primarily designed to facilitate one lung ventilation (OLV) in patients undergoing cardiac, thoracic, mediastinal, vascular, esophageal, or orthopedic procedures involving the chest cavity.  Lung isolation can be achieved by three different methods: double lumen tubes (DLT), bronchial blockers, or single-lumen endobronchial tubes. The most commonly used method is Double Lumen Tube. Nevertheless, malpositioning of the DLT is one of the most common problems and fiberoptic bronchoscopy has been recommended as a reliable method to avoid this complication. However, fiberoptic bronchoscopy is not always available. Fibreoptic bronchoscopy is an invasive method and carries risk of infection and airway trauma. Also, it demands expertise and knowledge of bronchial anatomy. Ultrasound has been proposed recently as a new method for detection of proper positioning of the endotracheal tube in critical care settings. Thoracic sonography can detect movement at visceral-parietal pleural interface (lung sliding) with normal ventilation while absence of such movement indicates lung collapse. Absence of lung sliding sign with demonstration of lung pulse (movement of pleura with cardiac activity) indicates complete atelectasis. These signs can be appreciated to confirm lung isolation in procedures involving OLV. This is a non-invasive, short, simple, bed side technique to confirm lung isolation following DLT placement and thus can confirm position of DLT.