question: BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is a once-in-century crisis to public health. Although the pathogen for COVID-19, the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has been identified, the pandemic is still ongoing. The critically ill COVID-19 patients account for most disease-associated death; thus, there is an urgent need to identify prognostic factors that would help determine therapeutic approaches. METHODS: In this study, we retrospectively analyzed the clinical and laboratory findings in 100 critically ill COVID-19 patients in Hubei Women & Children Healthcare Hospital (Guanggu District), of whom 22 patients died in hospital, and 78 patients survived. RESULTS: We found that age, lymphocyte count, and total bilirubin concentration were an independent prognostic factor for critically ill COVID-19 patients. Of particular importance, we observed a significant elevation of myocardium injury biomarkers, including CK-MB, high-sensitivity cardiac troponini I (hs-cTnI), and Mb, in the non-survivor group. These myocardium injury biomarkers appeared to correlate with the time of survival, and two multivariate models have suggested hs-cTnI was a novel prognostic factor with a sensitivity of 75.0% and a specificity of 84.9%. CONCLUSIONS: Altogether, our study highlighted the prognostic significance of myocardium injury biomarkers in critically ill COVID-19 patients. Monitoring myocardium injury biomarkers would predict patient survival and guide therapeutic strategy.