Background: There are various studies that suggest that short term and early prone positioning can increase PaO2/FiO2 in moderate to severe acute respiratory distress syndrome (ARDS). The aim of our study was to observe the effect of prone position on oxygenation status in spontaneously breathing non intubated covid19 patients on either non rebreathing mask (NRBM) or on noninvasive ventilation (NIV)