INTRODUCTION: Severe COVID-19 is associated with hypoxemic bilateral pneumonia that leads to mechanical ventilation in a considerable proportion of patients. To the best of our knowledge, there are no recommendations about the best time to initiate high flow nasal cannula (HFNC). PATIENTS AND METHODS: Retrospective study of all patients admitted for COVID-19 pneumonia who required HNFO between March 2020 and February 2021. Patients were grouped in early HNFC or late HNFC, according to the modified Kirby index. RESULTS: 53 patients were included. Forty-four of them were included in the early HFNC and 9 in late HNFC. There were no statistically significant clinical-epidemiological differences. Early use of HFNC was associated with a decrease in the need for intubation (29.5 vs. 66.6%, p = 0.044), hospital stay (18.8 d vs. 36 d, p = 0.022) and mortality (22.7 vs. 55.5%, p = 0.061). CONCLUSIONS: Early HFNC use is associated with a decrease in the need for intubation, mortality and overall hospital stay.