Premises: Acute respiratory failure caused by respiratory diseases, which is a frequent pathology in infants and young children, requires oxygen therapy, which can be administered by different devices. Objectives: To evaluate the efficiency of two devices for oxygen administration by determining a clinical appraisal score for acute respiratory failure in infants and young children by oxygen therapy using simple face masks and nasal cannulas. Material and methods: 74 children, aged between one month and 3 years were included in our study. Oxygen therapy was administered by face mask to 38 patients, and by nasal cannula to 36 patients. A clinical appraisal score of respiratory failure was calculated both before and after oxygen therapy. Oxygen saturation was measured by pulse oximetry (SpO 2 ) and arterial or capillary blood gas (SaO 2 ) before, and 30 minutes and 60 minutes after the initiation of oxygen therapy. Results: We found an improvement in the clinical score regardless of the method of administration; this improvement was more obvious at 60 minutes than at the 30 min evaluation (p < 0.001). The differences were statistically significant (p < 0.0001) for all the measurements (baseline vs. 30 minutes, baseline vs. 60 minutes, 30 minutes vs. 60 minutes). An increase in both SaO 2 and SpO 2 values was found (p < 0.001). Conclusions: The clinical score for acute respiratory failure and the SaO 2 and SpO 2 values significantly improved after oxygen therapy.