BACKGROUND AND AIMS: The health benefits of vitamin D are far beyond bone mineral metabolism. Vitamin D has immunomodulator and anti-inflammatory properties and its role in critically ill patients is controversial. The purpose of the study is to understand whether high doses of vitamin D supplementation are beneficial in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia hospitalized in a polyvalent intensive care unit (ICU) and correlate to all-cause mortality, need for invasive mechanical ventilation, and duration of hospitalization. METHODS: A retrospective study was conducted at a single polyvalent ICU, comparing patients supplemented with vitamin D with nonsupplemented patients. Eligible participants were adults with SARS-CoV-2 pneumonia admitted in this unit between April 14, 2020, and October 31, 2020. Demographic and clinical characteristics, comorbidities, and disease-related outcomes were extracted from electronic medical records. RESULTS: No statistically significant differences were observed between the groups in terms of need for invasive mechanical ventilation or duration of hospitalization. Supplementation with vitamin D was associated with lower all-cause ICU, intrahospital, and total mortality. CONCLUSION: High-dose vitamin D supplementation was associated with a reduction of mortality in patients with severe SARS-CoV-2 pneumonia. Randomized clinical trials are needed to confirm these findings and to assess the optimal dosage of supplementation.