Background and Aim: The new type of Severe Acute Respiratory Syndrome Coronavirus 2 (Coronavirus 2019- COVID-19) infection is the largest pandemic in the last decade. Acute respiratory distress syndrome is the complication with the highest mortality rate of this infection and there is no adequate treatment with proven efficacy to reduce mortality. This multi-center, retrospective study aimed to determine the effect of high-dose vitamin C on survival and other endpoints in invasively ventilated ARDS patients. Methods: This multi-center, observational retrospective cohort study was performed at five ICU centers between March 2020 and July 2020. Patients with ARDS due to COVID-19 who required IMV were included. High-dose vitamin C group was defined as patients who were treated with vitamin C over 200 mg/kg for four days. Patients who were not given vitamin C treatment were defined as the control group by using propensity score match analysis, as well. The groups were compared about the effects of high-dose vitamin C treatment on ICU mortality. Result: A total of 86 patients with a mean age of 67.85 ± 10.38 were included in the study. 72.1% of the patients were male. Forty-two (49%) patients were in the high dose vitamin C group, and 44 (51%) were in the control group. The mean PaO2/FiO2 at the time of admission to the ICU was 128.27±58.69 mmHg (133.63±56.51 mmHg in the control group, 122.36±61.18 mmHg in the study group, p=0.389). The mortality rate of high dose vitamin C group was lower than the control group (73.8% vs. 90.9%, p = 0.037,respectively). Conclusion: As an adjunctive therapy in invasively ventilated patients with COVID-19-associated ARDS, high doses of vitamin C may reduce mortality and development of organ damage. Prospective, randomized controlled studies with larger numbers of patients are needed to confirm these findings.