© 2015 Japan Pediatric Society.Background Delivery of supplemental oxygen is the initial vital management of hypoxemic acute lower respiratory infection (HALRI). Oxygen delivery systems include low-flow and high-flow devices. In high-flow devices such as the Venturi mask, a constant mixture of oxygen is delivered. As a result, increased rate of breathing does not affect the concentration of oxygen delivered. In this study, we compared the efficacy of oxygen masks and Venturi masks in the management of hypoxemia in pediatric patients. Methods A total of 65 children, aged 3-36 months, diagnosed with HALRI, were enrolled. Patients were allocated into groups, via simple alternate randomization, to receive oxygen through an oxygen mask or through a Venturi mask. Respiratory rate, heart rate, retraction, blood gas parameters, oxygen saturation, length of hospitalization, and oxygenation were recorded before and after oxygen treatment. Results After 24 h of treatment, respiratory rate was significantly lower among patients in the Venturi mask group compared with the oxygen mask group. Duration of supplemental oxygen and length of hospitalization were significantly lower in the Venturi mask group compared with the oxygen mask group. Conclusion In both groups, there was marked improvement in all measured parameters following introduction of supplemental oxygen. Oxygen was delivered more efficiently, however, by high-flow systems. The Venturi mask may decrease the total duration of oxygen usage time as well as the length of hospitalization among young children with HALRI through rapid symptom resolution.