1.1. Background: Covid-19 associated acute respiratory distress syndrome (CARDS) and prolonged mechanical ventilation im poses a major burden on affected critically ill individuals, in light of high mortality. We aimed to identify possible risk factors for mortality among the three categories of ARDS severity according to Berlin definition and to examine the effect of time on patients’ oxygenation and respiratory mechanics. 1.2. Methods: We prospectively investigated the clinical charac teristics and outcome of 196 consecutive mechanically ventilated patients with CARDS, along with oxygenation and respiratory me chanics, on ICU days 1, 3 and 7. 1.3. Results: ICU mortality accounted for 63.3%. Non-survivors were significantly older and presented higher disease severity on ICU admission and higher incidence of chronic obstructive pulmo nary disease (COPD), neurologic disease and immunosuppression. PaO2/FiO2 was significantly higher in the survivors group at all time points, whereas significant increase over time (day 7 vs day 1) was observed only in survivors group. Static respiratory system compliance was higher and driving pressure was lower in survi vors compared to non survivors, on days 3 and 7. Regarding the non-survivors group, oxygenation remained unchanged through different time points, while compliance reduced significantly and plateau and driving pressures increased through evolution of time. Mild, moderate and severe CARDS was reported in 16 (8.2%), 88 (44.9%) and 92 (46.9%) patients respectively. Incidence of obe sity was higher in severe CARDS. PEEP levels and plateau pres sures were higher in the severe CARDS, while respiratory system compliance and driving pressure did not differ among the CARDS categories. 1.4. Conclusions: In our case series, ICU mortality was high and increased accordingly to CARDS severity. Mortality risk factors included older age, COPD, neurological disorders and immuno suppression. Body mass index was significantly increased across CARDS severity. Trajectories of hypoxemia and respiratory me chanics were also associated with outcome