Lung ultrasound has become increasingly important in the evaluation of the thorax and its pathologies. It has proved to be very useful in the evaluation of hospitalized patients, allowing doctors to evaluate and make quick decisions, as well as providing guidance for diagnostic and therapeutic procedures. Ultrasound has many advantages over other studies since it can avoid transferring patients, and it is harmless, accessible and fast. In this article we will review basic concepts of lung ultrasound and its use in the diagnosis of pathologies. Key words: Pulmonary ultrasound; pleura; pneumothorax; pleural effusion.