Acute bronchiolitis is a common disease in children below 24 months of age. The most common aetiology of this disease is a respiratory syncytial virus infection. Since there is no effective treatment for bronchiolitis, supportive therapy alleviating symptoms and preventing respiratory failure is recommended. Oxygen therapy and appropriate nutrition during the disease are considered effective, particularly in severe cases. The choice of oxygen support is crucial. The present paper discusses oxygen therapy using high-flow nasal cannulas. Moreover, the safety of the method, its adverse side effects and practical pre-treatment guidelines are discussed.