Introduction: COVID-19 infection has spread with the development of the pandemic and is transmitted by respiratory droplets. Severe and critically ill patients may deteriorate rapidly and progress to multiple organ failure and death. It is imperative to determine the prognostic values associated with this disease. We aimed to test the strength of the bun/creatinine ratio in predicting mortality in critically ill patients in the infected group. Material and method: 158 patient data were included in our study after ethics committee approval. The blood results in intensive care units were analyzed, and the patients were grouped as group 1 and group 2. Age, gender, comorbid conditions, bun creatinine, and other blood values were compared statistically. With this comparison, the effects on mortality and clinical features were evaluated. Results: The study included 158 patients between Mar 31 and Dec 31, 2020. Routine blood tests were seen in these patients according to the intensive care evaluation criteria. It was observed that bun, creatinine, IL-6, CRP values were higher, and GFR, total protein values were lower in the patients who lost their lives. The bun/creatinine ratio was similar between the groups. Conclusion: It was found that urea and creatinine could help in demonstrating mortality in critical intensive care patients. The bun/creatinine ratio was not associated with mortality in covid 19 infected critical intensive care patients. Studies with larger numbers of patients are needed.