Placing the patient in prone position (i.e. lying flats with ventral side or chest side down) was first proposed in 1974 with the aim of improving the oxygenation specifically in patients with Acute respiratory distress syndrome. Several studies were conducted and following results are obtained from these studies: 1. Improved oxygenation specifically in patients with Acute respiratory distress syndrome. 2. Prone position helped in improving oxygenation by reducing the dorsal compression of lung 3. Enhanced lung perfusion 4. Better ventilation-perfusion matching 5. Decreased death rates in patients with severe hypoxemia 6. Decreased ventilator induced lung injury 7. Enhanced lung recruitment and decreased hyperinflation when compared with supine position Overall, the studies conducted were found to be in favour of prone position in mechanical ventilation.