Background: The COVID-19 pandemic has placed an enormous and growing burden on the population and health infrastructure, warranting innovative ways to mitigate risk of contracting and developing severe forms of this disease. A growing body of literature raises the issue of vitamin C and vitamin D as a risk-assessment tool, and therapeutic option, in COVID-19. Objective: The objective of this pilot study was to measure serum vitamin C and vitamin D levels in a cohort of patients with critical COVID-19 illness in our community hospital ICU, correlate with other illness risk factors (age, BMI, HgbA1c, smoking status), generate hypotheses, and suggest further therapeutic intervention studies. Method: This pilot study included all 21 critically ill COVID-19 patients hospitalized in May 2020 in the ICU of North Suburban Medical Center, Thornton, Colorado, in whose care the principal investigator (C.A.) was involved. We measured patients' serum vitamin C and vitamin D levels, and standard risk factors like age, BMI, HbA1c, and smoking status. Variables in this study were gauged using descriptive statistics. Results: Of 21 critically ill COVID-19 patients (15 males and 6 females, 17 Hispanic and 4 Caucasian, of median age 61 years, range 20-94), there were 11 survivors.Serum levels of vitamin C and vitamin D were low in most of our critically ill COVID-19 ICU patients.Older age and low vitamin C level appeared co-dependent risk factors for mortality from COVID-19 in our sample.Insulin resistance and obesity were prevalent in our small cohort, but smoking was not. Conclusion: Our pilot study found low serum levels of vitamin C and vitamin D in most of our critically ill COVID-19 ICU patients. Older age and low vitamin C level appeared co-dependent risk factors for mortality. Many were also insulin-resistant or diabetic, overweight or obese, known as independent risk factors for low vitamin C and vitamin D levels, and for COVID-19.These findings suggest the need to further explore whether caring for COVID-19 patients ought to routinely include measuring and correcting serum vitamin C and vitamin D levels, and whether treating critically ill COVID-19 warrants acute parenteral vitamin C and vitamin D replacement.