External High-Frequency Oscillation (EHFO) is one of the non-invasive methods of airway clearance used to help the release of phlegm in patients with chronic respiratory disorders such as cystic fibrosis, bronchiectasis, chronic obstructive pulmonary disease, and neuromuscular diseases. EHFO works by firing very fast vibrations through a cuirass that causes the oscillations to break the mucus that is sticking to the walls of the airways, thus making it easier for its mobilization and elimination. Besides, by facilitating the ciliary movement and lowering the mucus viscosity, EHFO can lead to better lung function, fewer exacerbation episodes, and a decreased risk of infection. Research show its effectiveness in breathing improvement and as a quality of life enhancer, especially in patients who find it difficult to perform other airway clearance techniques. Owing to its safety, tolerability, and efficacy, EHFO represents a cornerstone technique in the long-term management of chronic respiratory diseases characterized by mucus retention and hypersecretion.