Ultrasound techniques have been developed since the past century and are becoming more useful in different areas of medical knowledge. More recently, lung ultrasound gained importance throughout artefacts analysis to help clinical evaluation at bedside and became subject of interest in the paediatric intensive care and emergency department settings for both procedural and diagnostic purposes. The normal pattern of lung ultrasound is defined by the presence of lung sliding associated with A-lines whereas B-lines may be representative of pathologic findings. This review focuses on some of the most common pulmonary conditions, their respective sonographic features and clinical implications in the emergency department and paediatric intensive care unit.